how to formulate a research question using pico

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Defining the Question: Foreground & Background Questions

In order to most appropriately choose an information resource and craft a search strategy, it is necessary to consider what  kind  of question you are asking: a specific, narrow "foreground" question, or a broader background question that will help give context to your research?

Foreground Questions

A "foreground" question in health research is one that is relatively specific, and is usually best addressed by locating primary research evidence. 

Using a structured question framework can help you clearly define the concepts or variables that make up the specific research question. 

 Across most frameworks, you’ll often be considering:

• a who (who was studied - a population or sample)
• a what (what was done or examined - an intervention, an exposure, a policy, a program, a phenomenon)
• a how ([how] did the [what] affect the [who] - an outcome, an effect). 

PICO is the most common framework for developing a clinical research question, but multiple question frameworks exist.

PICO (Problem/Population, Intervention, Comparison, Outcome)

Appropriate for : clinical questions, often addressing the effect of an intervention/therapy/treatment

Example : For adolescents with type II diabetes (P) does the use of telehealth consultations (I) compared to in-person consultations  (C) improve blood sugar control  (O)?

Framing Different Types of Clinical Questions with PICO

Different types of clinical questions are suited to different syntaxes and phrasings, but all will clearly define the PICO elements.  The definitions and frames below may be helpful for organizing your question:

Intervention/Therapy

Questions addressing how a clinical issue, illness, or disability is treated.

"In__________________(P), how does__________________(I) compared to_________________(C) affect______________(O)?"

Questions that address the causes or origin of disease, the factors which produce or predispose toward a certain disease or disorder.

"Are_________________(P), who have_________________(I) compared with those without_________________(C) at_________________risk for/of_________________(O) over_________________(T)?" 

Questions addressing the act or process of identifying or determining the nature and cause of a disease or injury through evaluation.

In_________________(P) are/is_________________(I) compared with_________________(C) more accurate in diagnosing_________________(O)?

Prognosis/Prediction:

Questions addressing the prediction of the course of a disease.

In_________________(P), how does_________________(I) compared to_________________ (C) influence_________________(O)?

Questions addressing how one experiences a phenomenon or why we need to approach practice differently.

"How do_________________(P) with_________________(I) perceive_________________(O)?" 

Adapted from: Melnyk, B. M., & Fineout-Overholt, E. (2011). Evidence-based practice in nursing & healthcare: A guide to best practice. Philadelphia: Wolters Kluwer/Lippincott Williams & Wilkins.

Beyond PICO: Other Types of Question Frameworks

PICO is a useful framework for clinical research questions, but may not be appropriate for all kinds of reviews.  Also consider:

PEO (Population, Exposure, Outcome)

Appropriate for : describing association between particular exposures/risk factors and outcomes

Example : How do  preparation programs (E) influence the development of teaching competence  (O) among novice nurse educators  (P)?

SPIDER (Sample, Phenomenon of Interest, Design, Evaluation, Research Type)

Appropriate for : questions of experience or perspectives (questions that may be addressed by qualitative or mixed methods research)

Example : What are the experiences and perspectives (E) of  undergraduate nursing students  (S)  in clinical placements within prison healthcare settings (PI)?

SPICE (Setting, Perspective, Intervention/phenomenon of Interest, Comparison, Evaluation)

Appropriate for : evaluating the outcomes of a service, project, or intervention

Example : What are the impacts and best practices for workplace (S) transition support programs (I) for the retention (E) of newly-hired, new graduate nurses (P)?

PCC (Problem/population, Concept, Context)

Appropriate for : broader (scoping) questions

Example : How do nursing schools  (Context) teach, measure, and maintain nursing students ' (P)  technological literacy  (Concept))throughout their educational programs?

Background Questions

To craft a strong and reasonable foreground research question, it is important to have a firm understanding of the concepts of interest.  As such, it is often necessary to ask background questions, which ask for more general, foundational knowledge about a disorder, disease, patient population, policy issue, etc. 

For example, consider the PICO question outlined above:

"For adolescents with type II diabetes does the use of telehealth consultations compared to in-person consultations  improve blood sugar control ?

To best make sense of the literature that might address this PICO question, you would also need a deep understanding of background questions like:

• What are the unique barriers or challenges related to blood sugar management in adolescents with TII diabetes?
• What are the measures of effective blood sugar control?
• What kinds of interventions would fall under the umbrella of 'telehealth'?
• What are the qualitative differences in patient experience in telehealth versus in-person interactions with healthcare providers?
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Developing Your Question

Developing your research question is one of the most important steps in the review process. At this stage in the process, you and your team have identified a knowledge gap in your field and are aiming to answer a specific question, such as

• If X is prescribed, then Y will happen to patients?

OR assess an intervention

• How does X affect Y?

OR synthesize the existing evidence 

• What is the nature of X? ​

​​Whatever your aim, formulating a clear, well-defined research question of appropriate scope is key to a successful review. The research question will be the foundation of your review and from it your research team will identify 2-5 possible search concepts. These search concepts will later be used to build your search strategy. 

PICOT Questions

Formulating a research question takes time and your team may go through different versions until settling on the right research question.  A research question framework can help structure your systematic review question.  

PICO/T is an acronym which stands for

• P        Population/Problem
• I         Intervention/Exposure
• C        Comparison
• O       Outcome
• T       Time

Each PICO includes at least a P, I, and an O, and some include a C or a T. Below are some sample PICO/T questions to help you use the framework to your advantage. 

For an intervention/therapy

In _______(P), what is the effect of _______(I) on ______(O) compared with 

_______(C) within ________ (T)?

For etiology

Are ____ (P) who have _______ (I) at ___ (Increased/decreased) risk for/of_______ (O) compared with ______ (P) with/without ______ (C) over _____ (T)?

Diagnosis or diagnostic test

Are (is) _________ (I) more accurate in diagnosing ________ (P) compared with ______ (C) for _______ (O)?

For ________ (P) does the use of ______ (I) reduce the future risk of ________ (O) compared with _________ (C)?

Prognosis/Predictions

Does __________ (I) influence ________ (O) in patients who have _______ (P) over ______ (T)?

How do ________ (P) diagnosed with _______ (I) perceive ______ (O) during _____ (T)?

Melnyk B., & Fineout-Overholt E. (2010). Evidence-based practice in nursing & healthcare. New York: Lippincott Williams & Wilkins.

Ghezzi-Kopel, Kate. (2019, September 16). Developing your research question. (research guide). Retrieved from  https://guides.library.cornell.edu/systematic_reviews/research_question

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How to formulate the review question using PICO. 5 steps to get you started.

Home | Blog | How To | How to formulate the review question using PICO. 5 steps to get you started.

Covidence covers five key steps to formulate your review question using PICO

You’ve decided to go ahead. You have identified a gap in the evidence and you know that conducting a systematic review, with its explicit methods and replicable search, is the best way to fill it – great choice 🙌. 

The review will produce useful information to enable informed decision-making and to improve patient care. Your review team’s first job is to capture exactly what you need to know in a well-formulated review question.

At this stage there is a lot to plan. You might be recruiting people to your review team, thinking about the time-frame for completion and considering what software to use. It’s tempting to get straight on to the search for studies 🏃. 

Take it slowly: it’s vital to get the review question right. A clear and precise question will ensure that you gather the appropriate data to answer your question. Time invested up-front to consider every aspect of the question will pay off once the review is underway. The review question will shape all the subsequent stages in the review, particularly setting the criteria for including and excluding studies, the search strategy, and the way you choose to present the results. So it’s worth taking the time to get this right!

Let’s take a look at five key steps in formulating the question for a standard systematic review of interventions. It’s a process that requires careful thought from a range of stakeholders and meticulous planning. But what if, once you have started the review, you find that you need to tweak the question anyway? Don’t worry, we’ll cover that too ✅.

📌 Consider the audience of the review

Who will use this review? What do they want to know? How do they measure effectiveness? Good review teams partner with the people who will use the evidence and make sure that their research plan (or protocol) asks a question that is relevant and important for patients.

📌 Think about what you already know

How much do you need to know about the topic area at this stage? Ideally, enough to come up with a relevant, useful question but not so much that your knowledge influences the way in which you phrase it. Why? Because setting a review question when you are already familiar with the data can introduce bias by allowing you to direct the question in favour of achieving a particular result. In practice, the review team is very likely to have some knowledge of relevant studies and some preconceived ideas about how the treatments work. That’s fine – and it’s useful – but it’s also good practice to recognise the influence this knowledge and these ideas might have on the choice of question. Issues of bias will come up again as we work through the rest of these steps.

If not enough is known about the subject area to ask a useful question, you might undertake a scoping review . This is a separate exercise from a systematic review and is sometimes used by researchers to map the literature and highlight gaps in the evidence before they start work on a systematic review. 

📌 Use a framework

Faced with a heady mixture of concepts, ideas, aims and outcomes, researchers in every field have come up with question frameworks (and some great backronyms ) to help them. Question frameworks impose order on a complex thought process by breaking down a question into its component parts. A commonly used framework in clinical medicine is PICO:

👦 P opulation (or patients) refers to the characteristics of the people that you want to study. For example, the review might look at children with nocturnal enuresis.

💊 I ntervention is the treatment you are investigating. For example, the review might look at the effectiveness of enuresis alarms.

💊 C omparison, if you decide to use one, is the treatment you want to compare the intervention with. For example, the review might look at the effectiveness of enuresis alarms versus the effectiveness of drug therapy. 

📏 O utcomes are the measures used to assess the effectiveness of the treatment. It’s particularly important to select outcomes that matter to the end users of the review. In this example, a useful outcome might be bedwetting. (Helpfully, some clinical areas use standardised sets of outcomes in their clinical trials to facilitate the comparison of data between studies 👏.) 

But back to bedwetting. In our example, a PICO review question would look something like this:

“In children with nocturnal enuresis (population), how effective are alarms (intervention) versus drug treatments (comparison) for the prevention of bedwetting (outcome)?”

PICO is suitable for reviews of interventions. If you plan to review prognostic or qualitative data, or diagnostic test accuracy, PICO is unlikely to be a suitable framework for your question. In Covidence you can save your PICO for easy reference throughout the screening, extraction and quality assessment phases of your review.

📌 Set the scope

The scope of a review question requires careful thought. To answer the example PICO question above, the review would compare one treatment (alarms) with another (drug therapy). A broader question might consider all the available treatments for nocturnal enuresis in children. The broad scope of this question would still allow the review team to drill down and separate the data into groups of specific treatments later in the review process. And to minimise bias, the intended grouping of data would be pre-specified and justified in the protocol or research plan.

Broader systematic reviews are great because they summarise all the evidence on a given topic in one place. A potential disadvantage is that they can produce a large volume of data that is difficult to manage. 

If the size of the review has started to escalate beyond your comfort zone, you might consider narrowing the scope. This can make the size of the review more manageable, both for the review team and for the reader. But it’s worth examining the motivations for narrowing the scope more closely. Suppose we wanted to define a smaller population in the example PICO question. Is there a good reason (other than to reduce the review team’s workload) to restrict the population to boys with nocturnal enuresis? Or to children under 10 years old? On the basis of what is already known, could the treatment effect be expected to differ by sex or age of the study participants? 🤔 Be prepared to explain your choices and to demonstrate that they are legitimate. 

Some reviews with a narrow scope retrieve only a small number of studies. If this happens, there is a risk that the data collected from these studies might not be enough to produce a useful synthesis or to guide decision-making. It can be frustrating for review teams who have spent time defining the question, planning the methods, and conducting an extensive search to find that their question is unanswerable. This is another reason why it is useful for the review team to have prior knowledge of the subject area and some familiarity with the existing evidence. The Cochrane Handbook contains some useful contingencies for dealing with sparse data .

Covidence can help review teams to save time whatever the scope and size of the review. In Covidence, data can be grouped to the review team’s exact specification for seamless export into data analysis software. The intuitive workflow makes collaboration simple so if one reviewer spots a problem, they can alert the rest of the team quickly and easily.

📌 Adjust if necessary

Systematic reviews follow explicit, pre-specified methods. So it’s no surprise to learn that the review question needs to be considered carefully and explained in detail before the review gets underway. But what about the unknown unknowns – those issues that the review teams will have to deal with later in the process but that they cannot foresee at the outset, no matter how much time they spend on due diligence? 

Clearly, reviews need the agility to control for issues that the project plan did not anticipate – strict adherence to the pre-specified process when a good reason to deviate has come to light would carry its own risks for the quality of the review. So if an initial scan of, for example, the search results indicates that it would be sensible to modify the question, this can be done. The research plan might make explicit the process for dealing with these types of changes. It might also contain plans for sensitivity analysis , to examine whether these choices have any effect on the findings of the review. As mentioned above with regard to scope, it might be difficult to defend a data-driven change to the question. And as before, the issue is the risk of bias and the danger of producing a spurious result.

(Figure 4. Image from Eshun‐Wilson  I, Siegfried  N, Akena  DH, Stein  DJ, Obuku  EA, Joska  JA. Antidepressants for depression in adults with HIV infection. Cochrane Database of Systematic Reviews 2018, Issue 1. Art. No.: CD008525. DOI: 10.1002/14651858.CD008525.pub3. Accessed 27 May 2021.)

This blog post is part of the Covidence series on how to write a systematic review. 

Sign up for a free trial of Covidence today!

Laura Mellor. Portsmouth, UK

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Systematic Search for Systematic Review

• Formulate Research Question Using PICO
• Introduction
• Find Systematic Reviews (SR)
• Databases Selection for Conducting SR
• Step 1. Set Preferences in EndNote
• Step 2. Create Groups in EndNote
• Step 3. Export Search Results from Databases to EndNote
• Step 4. Add Name of Database to References
• Step 5. Remove Duplicate Records
• Step 6. Share References with Teammates
• Step 7. Find Full Text Articles
• [Optional] Export References to Excel

Worksheets for Documenting & Reporting Search Process

Here are some resources for you to document and report your search process in a systematic review. 

• Workbook for documenting systematic search
• PRISMA Flow Diagram A flow diagram to depict the flow of information through the different phases of a systematic review. It maps out the number of records identified, included and excluded, and the reasons for exclusions.

Understanding SR

• What are systematic reviews? (Cochrane)
• Intro to Systematic Reviews & Meta-Analyses
• Using PICO to formulate a search question   (CEBM)
• Turning search terms into a search   (CEBM)
• Turning your search strategy into results: PubMed demonstration   (CEBM)

Understanding study design

• What is a randomised trial?
• Epidemiology Study Types: Randomized Control Trial
• Epidemiology Study Types: Cohort and Case-Control
• Cohort, Case-Control, Meta-Analysis, Cross-sectional Study Designs & Definition 

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Except where otherwise noted, the content of this guide is licensed under a  CC BY-NC 4.0 License .

A systematic review aims to answer a specific research (clinical) question. A well-formulated question will guide many aspects of the review process, including determining eligibility criteria, searching for studies, collecting data from included studies, and presenting findings ( Cochrane Handbook , Sec. 5.1.1).

To define a  researchable  question, the most commonly used structure is  PICO , which specifies the type of P atient or P opulation, type of I nterventions (and C omparisons if there is any), and the type of O utcomes that are of interest. 

The table below gives an example on how a research question is framed using the PICO structure. You may also use the PICO components to write the objective and title of your review, and later to structure your inclusion and exclusion criteria for study selection. This ensures that the whole review process is guided by your research question. 

Type of Question and Study Design

While formulating your research question, it's also important to consider the  type of question  you are asking because this will affect the type of studies (or study design ) to be included in your review.

Each type of question defines its type of studies in order to provide the best evidence. For example, to answer a therapeutic question, you need to include as many Randomized Controlled Trials (RCTs) as possible, because RCTs are considered to have the highest  level of evidence  (least bias) for solving a therapeutic problem. 

The table below suggests the best designs for specific type of question. The Level of Evidence pyramid, which is widely adopted in the medical research area, shows a hierarchy of the quality of medical research evidence in different type of studies ( Level of Evidence (2011), Oxford Centre for Evidence-based Medicine, CEBM ).

Usually, the study design of a research work will be clearly indicated either in its title or abstract, especially for RCT. Some databases also allow to search or refine results to one or a few study designs, which helps you locate as many as possible the relevant studies. If you are not sure the study design of a research work, refer to this brief guide for spotting study designs  (by CEBM).

Learn to Build a Good Clinical Question

Learn to build a good clinical question  from this  EBP Tutorial: Module 1:  "Introduction to Evidence-Based Practice"

It is provided by Duke University and University of North Carolina at Chapel Hill, USA.

PICO Framework and the Question Statement The above named section  in the Library guide:  Evidence-Based Practice in Health , provided by the University of Canberra Library, explains the PICO framework with examples and in various question types.

Documenting Your Search Process

Systematic review requires a detailed and structured reporting of the search strategy and selection criteria used in the review. Therefore we strongly advise you to document your search process from the very beginning. You may use this workbook  to help you with the documentation.

The documentation should include:

• Research concepts in PICO structure and research question ,
• Type of studies you intend to include, and
• Inclusion and exclusion criteria in PICO structure

and the whole search process, including:

• Databases searched (hosting platforms) , including journals and other sources covered in handsearching
• Date of search
• Search strategy , including keywords and subject headings used, the combination of searches (usually copy-paste from database search page)
• Filters used in initial search or refine results, including year coverage, type of studies, age, etc.
• Number of results retrieved after each search and refinement in each database
• Total number of results from all databases searched
• Duplicates identified from all results
• Number of results with full text

Eventually, you will need to include the information above when you start writing your review. A highly recommended structure for reporting the search process is the PRISMA Flow Diagram . You may also use PRISMA Flow Diagram Generator to generate a diagram in a different format (based on your input). 

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Evidence - Based Practice

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EBP Process

1. Ask a clear clinical question

2. Acquire  best available evidence

3. Appraise  evidence for quality

4. Apply  evidence to practice

5. Assess  the outcomes

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• Importance of the PICO Question
• Formulating a Well Built Clinical Question
• Locating Evidence using P I C O Questions

The PICO question is a different way to think about the clinical questions that arise during patient care. Unlike informational questions, these questions are quite complex and sometimes a challenge to formulate. They are comprised of specific types of components, or concepts, and have a purpose throughout the EBP process.

The PICO Formula

It is not coincidence that this process is called formulating. When you formulate a PICO question, you are creating a formula that does several things:

• Focus the question by identifying the components or concepts in the question
• Defines the concepts that will be used when performing a complex literature search
• Used to ascertain which articles in a search retrieval best address the question
• Helps determine if studies found address the components of the original question
• Ultimately the process will provide the information needed to make a decision whether the intervention in the PICO question should be implemented

According to the Centre for Evidence Based Medicine (CEBM) , "one of the fundamental skills required for practicing EBM is the asking of well-built clinical questions. To benefit patients and clinicians, such questions need to be both directly relevant to patients' problems and phrased in ways that direct your search to relevant and precise answers."

A well-built clinical foreground question should have 4 components. The PICO model is a helpful tool that assists you in organizing and focusing your foreground question into a searchable query. Dividing into the PICO elements helps identify search terms/concepts to use in your search of the literature.

P = Patient, Problem, Population (How would you describe a group of patients similar to you? What are the most important characteristics of the patient?)

I = Intervention, Prognostic Factor, Exposure (What main intervention are you considering? What do you want to do with this patient? What is the main alternative being considered?)

C = Comparison (Can be None or placebo.) (What is the main alternative to compare with the intervention? Are you trying to decide between two drugs, a drug and no medication or placebo, or two diagnostic tests?)

O= Outcome (What are you trying to accomplish, measure, improve or affect? Outcomes may be disease-oriented or patient-oriented.)

• Nursing - Forming Focused Questions Using PICO by Cynthia Hunt Last Updated Feb 16, 2024 68 views this year

Locating evidence in literature depends upon asking an effective research question. Use the PICO mnemonic to build that question.

     P  -- patient, population, participant       I  -- intervention, therapy      C  -- comparison  ( not always required )      O  -- outcome

  4 Types of PICO Questions

     1. Diagnosis      2. Prognosis      3. Therapy      4. Etiology       

Diagnosis PICO : In children with respiratory infection, is the respiratory rate as effective as chest x-ray in detecting pneumonia? Prognosis PICO : In premature infants (compared to full-term infants), what is the lifetime prevalence of hearing deficit?

Therapy PICO : In patients with recurrent infection, do antibiotics, compared to no treatment, reduce recurrence rate?

Etiology PICO : In post-menopausal women, does hormone replacement therapy increase the risk of breast cancer?

PICO can be a useful tool for asking focused clinical questions.

PICOTT can also be used where T = type of question (eg. therapy) T = type of study (cohort, RCT, etc.)

PICO will help to clarify the question, determine the search concepts and type of study that is most appropriate to answer the question type.

• Introduction to Evidence Based Practice Duke University
• PICO Question - Asking questions

PICO Question Formats:

 Fill in the blanks with information from your clinical scenario: THERAPY In_______________, what is the effect of ________________on _______________ compared with _________________?

PREVENTION For ___________ does the use of _________________ reduce the future risk of ____________ compared with ______________? DIAGNOSIS OR DIAGNOSTIC TEST Are (Is) ________________ more accurate in diagnosing _______________ compared with ____________? PROGNOSIS Does ____________ influence ______________ in patients who have _____________? ETIOLOGY Are ______________ who have _______________ at ______________ risk for/of ____________ compared with _____________ with/without______________? MEANING How do _______________ diagnosed with _______________ perceive __________________? Melnyk, B. M., & Fineout-Overholt, E. (2011). Evidence-based practice in nursing & healthcare: A guide to best practice. Philadelphia: Wolters Kluwer/Lippincott Williams & Wilkins.

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PICO- What's in a queston?

The PICOT question format is a consistent "formula" for developing answerable, researchable questions.

Note: Not every question will have an intervention (as in a meaning question) or time (when it is implied in another part of the question) component.

PICO(T) Templates

Template for Asking PICOT Questions

For an intervention/therapy:

In _______(P), what is the effect of _______(I) on ______(O) compared with _______(C) within ________ (T)?

For etiology:

Are ____ (P) who have _______ (I) at ___ (Increased/decreased) risk for/of_______ (O) compared with ______ (P) with/without ______ (C) over _____ (T)?

Diagnosis or diagnostic test:

Are (is) _________ (I) more accurate in diagnosing ________ (P) compared with ______ (C) for _______ (O)?

Prevention:

For ________ (P) does the use of ______ (I) reduce the future risk of ________ (O) compared with _________ (C)?

Prognosis/Predictions

Does __________ (I) influence ________ (O) in patients who have _______ (P) over ______ (T)?

How do ________ (P) diagnosed with _______ (I) perceive ______ (O) during _____ (T)?

Melnyk B., & Fineout-Overholt E. (2010). Evidence-based practice in nursing & healthcare. New York: Lippincott Williams & Wilkins.

Develop your Research Question

The PICO(T) Question

A clinical question that is composed using the PICO or PICOT format will help you to focus your search and help you to develop your research skills which are essential in finding the best available evidence.

The most common PICO(T) elements are:

P - Population

• How you would describe a group of people with a similar problem or complaint.

I - Intervention

• How you plan to treat, medicate, diagnose and/or observe the patient's care.

C - Comparison (if applicable)

• The main intervention alternative you are considering (i.e. placebo, alternative therapy, different drug, surgery).

O - Outcome

• The result from proposed treatment that is measurable, including improvement of symptoms,no symptoms, or complications.

(T) - Time (if applicable)

• The time frame of treatment and/or measurable outcome.

In order be successful in using Evidence Based Practice (EBP) you will need to learn how to develop well-composed clinical questions.  By formatting your research question in a PICO(T) format you can gather evidence relevant to your patient's problem.   Well-composed PICO(T) questions generally contain up to four components each represented in the acronym  " PICO(T)"  P=Patient or Population and Problem; I=Intervention or Indicator; C=Comparison or Control (not part of all questions); O=Outcome; T=Time or Type.

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• Research Process

Clinical Questions: PICO and PEO Research

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When you’re beginning the clinical research process, one of your first decisions will be around framing your clinical question. That, in turn, will depend on if your research is quantitative, or based on numerical data, or qualitative research based on non-numerical data. A PICO clinical question is tied to quantitative data, whereas a PEO question relates to qualitative data.

Let’s take a look at both of these clinical question formats.

What is a PICO Question?

As mentioned above, a PICO research question is used when quantitative data is involved. PICO stands for:

• P – Population, Patient and/or Problem: How do you describe the patients, people or the problem that you’re looking at?
• I – Intervention: What are you considering for an intervention, exposure or factor?
• C – Comparison: Do you have something to compare to the intervention, exposure or factor that you’re considering?
• O – Outcome: What are you hoping to measure, improve, affect or accomplish?

So, essentially, your PICO question will answer the above aspects. This type of clinical question is most often used when the research is investigating evidence-based medicine or other interventions. However, the PICO question format can also be used for non-clinical settings, such as psychological interventions for school-age children, and how they relate to academic achievement.

How to Write a PICO Question

It can sometimes be a challenge to write PICO Questions, as they can be very complex. Since we are looking at evidence-based conclusions, great thought has to be put into formulating a PICO research question. Once the question has been written and clarified, it can help the researcher determine what type of study model will work best to answer the question. So, in a very real way, asking the question properly helps you select what type of study you’ll be conducting.

Fortunately, once you are comfortable with the elements of a PICO question, it almost becomes a plug and play model. For example, if you are looking at questions around prognosis, you might structure your PICO question like this:

Would ________________ (I) affect or influence _________________________ (O) with patients or people who have ___________________________________________________ (P) compared to __________________________(C)?

Another example of a PICO research question might include an inquiry into prevention:

With ___________________ (P) does the practice or use of ________________________ (I) reduce or prevent risk of __________________________(O), compared with __________________________(C)?

What is a PEO Question?

A PEO research question focuses on non-numerical data, or qualitative research. Here, relationships and associations are explored. For example, a PEO question can try to explore whether there is a correlation between taking baby aspirin and a lowered risk of heart attacks.

PEO stands for:

• Population: Who are you studying? Infants? Males who are between the ages of 55 and 60? Adolescent females?
• Exposure: What is your population exposed to? Baby aspirin? Soy supplements? Peanuts?
• Outcome: What is the result of the exposure on your population? Lowered risk for heart attacks? Food allergies? Increased menstrual cramps?

How to Write a PEO Question

Writing a PEO question isn’t generally as complex as writing a PICO question, since you’re only looking at what population, what they’re exposed to, and what your expected outcome is. For example, if you’re looking at food allergies in infants, your PEO question might look like this:

In infants between the age of 6 to 9 months (P), is there an association between exposure to micro-doses of common food allergens (E) and reduced childhood food allergies? (O)

Similar questions can be explored this way:

In or with ___________________ (P), will ________________________(E) result in _________________________ (O)?

Using PICO and PEO Research Questions for Literature Reviews of Searching

Just as you might utilize PICO and PEO question formatting for designing your research, you can also tap into their formats when you’re looking for previous studies on your topic of interest. For example, if you are looking for information on dietary interventions and type 2 diabetes reversal, you can use keywords related to the formulation of a research question:

P: Individuals with type 2 diabetes E: Mediterranean Diet O: Reversal of type 2 diabetes

To find research related to the above question, you would pull out keywords, like:

“type 2 diabetes,” “reversal” and “Mediterranean Diet”

Clinical Question Formats

There are a wide variety of clinical question formats, in addition to PICO and PEO. These can include PICO(T), which adds a “time-frame” ingredient, and (P)PICO if your population is more complex, like white males, age 50-55.

The bottom line is that an effective clinical research question needs to be relevant to the patient or problem, and worded in a way that it’s easy for those looking for your research to find it. If you’re designing a research project, starting with an effective and well-written clinical research question is a critical first step.

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Evidence-Based Practice: PICO

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Focusing Clinical Questions

A clinical question needs to be directly relevant to the patient or problem at hand and phrased in such a way as to facilitate the search for an answer. PICO makes this process easier. It is a mnemonic for the important parts of a well-built clinical question. It also helps formulate the search strategy by identifying the key concepts that need to be in the article that can answer the question.

PICO or PICOTT:

PATIENT OR PROBLEM How would you describe a group of patients similar to yours? What are the most important characteristics of the patient?

INTERVENTION, EXPOSURE, PROGNOSTIC FACTOR What main intervention, exposure, or prognostic factor are you considering? What do you want to do with this patient?

COMPARISON What is the main alternative being considered, if any?

OUTCOME What are you trying to accomplish, measure, improve or affect?

Type of Question Therapy / Diagnosis / Harm / Prognosis / Prevention

Type of Study Systematic review / RCT / cohort study / case-control

• The well-built clinical question: a key to evidence-based decisions Richardson, WS. et al. ACP Journal Club, v123:A12, Nov-Dec, 1995.

Types of Questions

Primary Question Types

• Therapy: how to select treatments to offer our patients that do more good than harm and that are worth the efforts and costs of using them.
• Diagnostic tests : how to select and interpret diagnostic tests, in order to confirm or exclude a diagnosis, based on considering their precision, accuracy, acceptability, expense, safety, etc.
• Prognosis : how to estimate a patient's likely clinical course over time due to factors other than interventions
• Harm / Etiology: how to identify causes for disease (including its iatrogenic forms).

Other Question Types

• Clinical findings: how to properly gather and interpret findings from the history and physical examination.
• Clinical manifestations of disease: knowing how often and when a disease causes its clinical manifestations and how to use this knowledge in classifying our patients' illnesses.
• Differential diagnosis: when considering the possible causes of our  patient’s clinical problem, how to select those that are likely, serious and responsive to treatment.
• Prevention: how to reduce the chance of disease by identifying and modifying risk factors and how to diagnose disease early by screening.
• Qualitative:  how to empathize with our patients’ situations, appreciate the meaning they find in the experience and >understand how this meaning influences their healing.

From: Sackett, DL. Evidence-based medicine: how to practice and teach EBM .

Clinical Question + Study Design

The type of question will often dictate the best study design to address the question. In the absence of the best study design, move down the hierarchy of evidence:

*it is not always ethical to randomize people to a known harmful exposure. However, some RCTs do contain information on adverse events, side effects, etc. that could be helpful in answering certain clinical questions regarding harms. 

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PICO Research Questions: Formulating a PICO Question

• Getting Started

Formulating a PICO Question

• PICO in the Databases
• Levels of Evidence
• Online Resources
• Breaking Down PICO
• Background & Foreground Questions
• Inclusion & Exclusion

How do I Break Down a PICO Question?

You first need to come up with a question that includes all of the PICO components and break those down for searching the database.

For example:  In non-ambulatory patients, (P) does turning the patient (I) compared to pressure mattresses (C ) reduce the risk of pressure ulcers? (O)

To search for evidence-based articles related to your PICO question, identify the keywords for each PICO element.

• P  – Patient, non-ambulatory
• I  – turning
• C  – pressure mattress
• O  – pressure ulcer

Turn these keywords into  subject descriptors  or  MeSH/CINAHL subject headings  to use in your database searches.

Ask background questions   and foreground questions.

• Typically found in textbooks, encyclopedia, or reviews.
• Not normally asked when clinical decisions are needed to be made about a patient.
• Typically found in journals and conference proceedings.
• Require a grasp of the basic concepts from background questions

Think about inclusion and exclusion criteria to help you select and set boundaries for your searching.

• Certain types of studies.
• Certain geographic locations.
• Published within last 5 years.
• Comparison of certain treatments.
• Use of wrong types of studies.
• Published more than 5 years ago.
• Published in another language (depending on if you can read the language or are looking for articles only pertaining to the U.S.).
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Evidence-Based Practice (EBP)

• The EBP Process
• Forming a Clinical Question
• Inclusion & Exclusion Criteria
• Acquiring Evidence
• Appraising the Quality of the Evidence
• Writing a Literature Review
• Finding Psychological Tests & Assessment Instruments

The PICO(T) Chart

When searching for evidence-based practice studies in the Nursing and Medical databases, you must first develop a  well-built clinical question . Below is a chart to guide you in formulating a question by breaking it down to its most important parts.

Students sometimes have difficulty incorporating classroom skills into the clinical setting. The PICO(T) Chart provides an easy framework for integrating clinical information into the development of a research question. Students can complete the following worksheet, incorporating detailed information into each response.

Decide what your research interest or topic is and then develop a research question to answer it.

Design a question that incorporates the most salient piece of information from each of the above categories.

PICO Template Questions

The PICO framework is ideal for building questions that focus on comparing treatments . Other types of questions—especially those focused on prognosis, etiology, or perceptions—can be more challenging. Just remember that the Intervention portion usually represents the piece of your research you're interested in comparing or controlling; if you were designing an experiment, it would be the piece that you manipulate to see what results you'd get. 

You may find it helpful to use one of the following templates when creating your PICO question. Remember, the time (T) piece is usually optional and therefore can be omitted.

Treatment (therapy) — questions addressing the treatment of an illness or disability:

In _______(P), how does _______(I) compared with _______(C) affect _______(O) within _______(T)?

In _______(P), what is the effect of _______(I) on _______(O) compared with _______(C)?

Ex 1: In African American female adolescents with hepatitis B (P), how does acetaminophen (I) affect liver function (O) compared with ibuprofen (C)? Ex 2: In inpatient chronic schizophrenia patients (P), do social skills group training sessions (I) increase conversational skills (O) when compared with standard care (C)?

Prevention  — questions addressing the prevention of a risk factor or problematic health condition:

In _______(P), does the use of _______(I) reduce the incidence [or future risk] of _______(O) compared with _______(C)?

Ex: In adult females (P), do daily vitamin C or zinc supplements (I) reduce the incidence of the common cold (O) compared with no intervention (C)?  

Diagnosis — questions addressing the process of determining the nature and cause of a disease or injury through evaluation:

In _______(P) is/are _______(I) more accurate in diagnosing _______(O) compared with _______(C)?

Ex: In middle-aged males with suspected myocardial infarction (P), are serial 12-lead ECGs (I) more accurate in diagnosing an acute myocardial infarction (O) compared with one initial 12-lead ECG (C)?  

Prognosis (natural history) — questions addressing the prediction of the course of a disease:

In _______(P) how does _______(I) compared with _______(C) influence _______(O) over/during _______(T)?

Does _______(I) influence _______(O) in patients who have _______(P) over _______(T)?

Ex 1: In patients 65 years and older (P), how does the use of an influenza vaccine (I) compared with not receiving the vaccine (C) influence the risk of developing pneumonia (O) during flu season (T)? Ex 2: In patients who have experienced an acute myocardial infarction (P), how does being a smoker (I) compared with being a non-smoker (C) influence death and infarction rates (O) during the first 5 years after the myocardial infarction (T)?  

Etiology or harm (causation) — questions addressing the causes or origin of disease, the factors that produce or predispose toward a certain disease or disorder:

Are _______(P) who have _______(I) at increased/decreased risk of _______(O) compared with those who have/do not have _______(C) over/during _______(T)?

Ex: Are 30- to 50-year-old women (P) who have high blood pressure (I) at increased risk for an acute myocardial infarction (O) compared with those without high blood pressure (C) during the first year after hysterectomy (T)?

Meaning or quality of life — questions addressing how one experiences a phenomenon:

How do _______(P) diagnosed with _______(I) perceive _______(O) compared with _______(C) during/over _______(T)?

Ex 1: How do young males (P) diagnosed with below-the-waist paralysis (I) perceive their interactions with their romantic partners (O) during the first year after their diagnosis (T)? Ex 2: How do pregnant women (P) newly diagnosed with diabetes (I) perceive reporting their blood sugar levels to their healthcare providers (O) during their pregnancy and six weeks postpartum (T)?

Adapted from the PICOT Question Template, Ellen Fineout-Overholt, 2006. This form may be used for educational and research purposes without permission.

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Formulating a Clinical Question: PICO

PICO  is a popular framework for formulating clinical questions , especially those relating to therapy (or intervention) effectiveness.  It’s used to develop a well-built clinical question to aid in creating a search strategy. It helps identify searchable aspects of a situation in which a patient or population has a certain condition, and the outcome of interest is related to a therapy or intervention. 

PICO stands for:

• P – Populations/People/Patient/Problem
• I – Intervention(s)
• C – Comparison (if any)
• O – Outcome

For this scenario, we can build our PICO question like this:

P- premature infants in the NICU

I-  music therapy

C- no comparison (null comparison)

O- Improvement in physiological and behavioral responses

Using PICO, we can formulate a focused, answerable question:

• PICO Worksheet and Search Strategy for CINAHL This form is adapted from Purdue University Libraries.
• PICO Tool for PubMed Searching A quick way of searching your PICO question in PubMed. Enter the population and intervention, comparison and/or outcome (if appropriate).You can also select the type of publications you are interested in such as RCTs or systematic reviews. May be useful for scoping searches to find key studies and to get an idea of the potential size of the evidence base. Not recommended for fully comprehensive searches for systematic reviews as the searcher has no control over or evidence of the search strategy for reporting purposes.

Brown, D. (2020). A Review of the PubMed PICO Tool: Using Evidence-Based Practice in Health Education.  Health Promotion Practice ,  21 (4), 496–498.

Source:  Showmetheevidence.com

• Answering Clinical Questions A flowchart from the Centre for Evidence Based Medicine.
• Evidence Based Prace Question Development & Search Checklist By Roy E. Brown, Virginia Commonwealth University.

Checklist  from From Roy E, Brown, Virginia Commonwealth University. This checklist is distributed under a  Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0) License  (https://creativecommons.org/licenses/by-nc-sa/4.0/).

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• EBP in Nursing: More Resources
• Question Types
• Levels of Evidence
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• Study Types & Terminology
• Quantitative vs. Qualitative Research
• Critical Appraisal: Evaluating Studies
• Conducting a Systematic Review
• Research Study Design
• Selected Print and Electronic Reference Books for EBP
• Finding a Book on the Shelf by Call Number
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• Selected Evidence Based Practice Journals
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• Databases for EBP
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• Sample Annotated Bibliography
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Using PICO or PICOT: How to Formulate a Search Question: Home

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Using the PICO format

• Constructing a Focused, Well-Articulated Question A brief description of how to formulate a search question using the PICO format.

Using the PICOT format

• What is your research question? An introduction to the PICOT format for clinicians
• PICO Worksheet

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Evidence-Based Practice in Health

• Introduction
• PICO Framework and the Question Statement

Using the PICO Framework

Writing your question statement.

• Types of Clinical Question
• Hierarchy of Evidence
• Selecting a Resource
• Searching PubMed
• Module 3: Appraise
• Module 4: Apply
• Module 5: Audit
• Reference Shelf

PICO Framework

Without a well-focused question, it can be very difficult and time consuming to identify appropriate resources and search for relevant evidence. Practitioners of Evidence-Based Practice (EBP) often use a specialized framework, called PICO , to form the question and facilitate the literature search. 1 PICO stands for:  

• P atient Problem, (or Population)
• I ntervention,
• C omparison or Control, and

When forming your question using PICO , keep the following points in mind:

• Your P atient is a member of a population as well as a person with (or at risk of) a health problem. So, in addition to age and gender, you may also need to consider ethnicity, socioeconomic status or other demographic variables.
• A C omparison is not always present in a PICO analysis.
• O utcomes should be measurable as the best evidence comes from rigorous studies with statistically significant findings.
• An O utcome ideally measures clinical wellbeing or quality of life, and not alternates such as laboratory test results.

PICO Elements Change According to Question Type (Domain)

When forming your question using the PICO framework it is useful to think about what type of question it is you are asking, (therapy, prevention, diagnosis, prognosis, etiology). The table below illustrates ways in which P roblems, I nterventions, C omparisons and O utcomes vary according to the t ype (domain) of your question. 2

Once you have clearly identified the main elements of your question using the PICO framework, it is easy to write your question statement.  The following table provides some examples.

1. Schardt, C., Adams, M. B., Owens, T., Keitz, S., & Fontelo, P. (2007). Utilization of the PICO framework to improve searching PubMed for clinical questions. BMC Medical Informatics and Decision Making , 7, 16. doi: http://dx.doi.org/10.1186/1472-6947-7-1

2. Fineout-Overholt, E., & Johnston, L. (2005). Teaching EBP: asking searchable, answerable clinical questions. Worldviews On Evidence-Based Nursing , 2, 157-160.

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EBP Learning Module

Ask the Question

Formulating a question using pico.

Often our need for information is not formulated as a question to begin with - but if you don't ask a question, it is probably fair to say you will not get an answer! Asking the right question is an important start to finding the information needed to inform clinical practice.

Structuring the question is the first step. Vague, broad, poorly framed questions will most likely result in lost time and an inability to locate useful evidence. In comparison, asking a specific and focused question enables the development of relevant keywords and an effective search strategy.

Most questions can be broken down into three or four components that describe the population, the intervention or treatment (and sometimes an alternative treatment), and the outcome you want to investigate. This is known as the PICO method, and it is widely used by health researchers, healthcare professionals, and related collaborations such as those in The Cochrane Library, to construct searchable questions that give relevant and precise results.

The table below shows how the PICO method is used.

The acronym is sometimes given as PICOT where T stands for time, type of study, or test; or PECOT where E stands for the exposure group, C for the control group and T for time, type of study, or test.

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• Course Home
• What is Evidence-Based Practice?
• Using PubMed to Support Evidence-Based Practice

Using PICO to Frame Clinical Questions

• Using PICO to Identify Search Terms
• Perform a PubMed Search
• Connect Search Terms to MeSH Terms
• Filter PubMed Search Results
• Perform a Clinical Queries Search and Filter Results
• Use the Systematic Review Filter
• Scenario Practice
• Additional Resources

How to Navigate This Course

There are a variety of ways you can navigate this training. You can:

• Click the Back and Next buttons at the bottom of each page to move through the material
• Use the main navigation with dropdown subsections featured on all pages
• Use a combination of the above methods to explore the course contents

Develop a Clinical Question

To use evidence-based practice, you need a clear idea of the question you would like to answer. PICO is an acronym to help you formulate a clinical question and guide your search for evidence. Using this formula can help you find the best evidence available in a quicker, more efficient manner. Click on each letter for a description.

Patient or Problem

P = patient or problem.

How would you describe the patient? What issue are they experiencing?

Intervention

I = intervention.

What would you like to do to help the patient?

C = Comparison

What would be the alternative to the intervention you selected?

O = Outcome

By doing the intervention, what do you hope to accomplish?

Think about the following scenario and use PICO to create a clinical question:

Physicians in your office recommend exercise to patients age 65 and older who have high blood pressure. However, you overhear patients express doubts. One patient tells his spouse that he does not know how exercise will help. Will patients follow their physicians’ recommendations for exercise? You are considering whether creating handouts and holding a class on the benefits of physical activity might encourage patients to exercise.

Using PICO, we identify:

P = Patient or Problem - Patients age 65 and older with high blood pressure

I = Intervention - Patient education

C = Comparison - No patient education

O = Outcome - Patient participation in exercise

From this list, we develop the clinical question, “Are patient education programs effective (compared to no intervention) in increasing patient exercise in the population of patients age 65 and older with high blood pressure?”

(Image Source: iStock Photos, fstop123©)

Try-It Exercise

Identify the PICO elements from the following scenario:

As a school nurse in a local high school, you notice an increase in teens that are vaping. You’d like to do some research into the possible negative health effects of vaping so that you can provide students with factual materials to help them stop or reduce their smoking.

Exercise - P

P = Patient or Problem - High-school students (teenagers)

Exercise - I

I = Intervention - Providing materials on negative health effects

Exercise - C

C = Comparison - Not providing materials on negative health effects

Exercise - O

O = Outcome - Help students stop or reduce smoking

Systematic Reviews: Formulate your question and protocol

• Formulate your question and protocol
• Developing the review protocol
• Searching for evidence
• Search strategy
• Managing search results
• Evaluating results (critical appraisal)
• Synthesising and reporting
• Further resources

This video illustrates how to use the PICO framework to formulate an effective research question, and it also shows how to search a database using the search terms identified. The database used in this video is CINAHL but the process is very similar in databases from other companies as well.

Recommended Reading

• BMJ Best Practice Advice on using the PICO framework.

A longer on the important pre-planning and protocol development stages of systematic reviews, including tips for success and pitfalls to avoid. 

* You can start watching this video from around the 9 minute mark.*

Formulate Your Question

Having a focused and specific research question is especially important when undertaking a systematic review. If your search question is too broad you will retrieve too many search results and you will be unable to work with them all. If your question is too narrow, you may miss relevant papers. Taking the time to break down your question into separate, focused concepts will also help you search the databases effectively.

Deciding on your inclusion and exclusion criteria early on in the research process can also help you when it comes to focusing your research question and your search strategy.

A literature searching planning template can help to break your search question down into concepts and to record alternative search terms. Frameworks such as PICO and PEO can also help guide your search. A planning template is available to download below, and there is also information on PICO and other frameworks ( Adapted from: https://libguides.kcl.ac.uk/systematicreview/define).

Looking at published systematic reviews can give you ideas of how to construct a focused research question and an effective search strategy.

Example of an unfocused research question: How can deep vein thrombosis be prevented?

Example of a focused research question: What are the effects of wearing compression stockings versus not wearing them for preventing DVT in people travelling on flights lasting at least four hours.

In this Cochrane systematic review by Clarke et al. (2021), publications on randomised trials of compression stockings versus no stockings in passengers on flights lasting at least four hours were gathered. The appendix of the published review contains the comprehensive search strategy used.  This research question has focused on a particular method (wearing compression stockings) in a particular setting (flights of at least 4 hrs) and included only specific studies (randomised trails). An additional way of focusing a question could be to look at a particular section of the population.

Clarke  M. J., Broderick  C., Hopewell  S., Juszczak  E., and Eisinga  A., 20121. Compression stockings for preventing deep vein thrombosis in airline passengers. Cochrane Database of Systematic Reviews 2021, Issue 4. Art. No.: CD004002  [Accessed 30th April 2021].  Available from: 10.1002/14651858.CD004002.pub4

There are many different frameworks that you can use to structure your research question with clear parameters. The most commonly used framework is PICO:

• Population This could be the general population, or a specific group defined by: age, socioeconomic status, location and so on.
• Intervention This is the therapy/test/strategy to be investigated and can include medication, exercise, environmental factors, and counselling for example. It may help to think of this as 'the thing that will make a difference'.
• Comparator This is a measure that you will use to compare results against. This can be patients who received no treatment or a placebo, or people who received alternative treatment/exposure, for instance.
• Outcome What outcome is significant to your population or issue? This may be different from the outcome measures used in the studies.

Adapted from:  https://libguides.reading.ac.uk/systematic-review/protocol

• Developing an efficient search strategy using PICO A tool created by Health Evidence to help construct a search strategy using PICO

Other Frameworks: alternatives to PICO

As well as PICO, there are other frameworks available, for instance:

• PICOT : Population, Intervention, Comparison, Outcome, Time.
• PEO: Population and/or Problem, Exposures, Outcome
• SPICE: Setting, Population or Perspective, Intervention, Comparison, Evaluation
• ECLIPS: Expectations, Client Group, Location, Impact, Professionals Involved, Service
• SPIDER: Sample, Phenomenon of interest, Design, Evaluation, Research type

This page from City, University of London, contains useful information on several frameworks, including the ones listed above.

Develop Your Protocol

Atfer you have created your research question, the next step is to develop a protocol which outlines the study methodology. You need to include the following:

• Research question and aims
• Criteria for inclusion and exclusion
• search strategy
• selecting studies for inclusion
• quality assessment
• data extraction & analysis
• synthesis of results
• dissemination

To find out how much has been published on a particular topic, you can perform scoping searches in relevant databases. This can help you decide on the time limits of your study.

• Systematic review protocol template This template from the University of Reading can help you plan your protocol.
• Protocol Guidance This document from the University of York describes what each element of your protocol should cover.

Register Your Protocol

It is good practice to register your protocol and often this is a requirement for future publication of the review.

You can register your protocol here:

• PROSPERO: international prospective register of systematic review
• Cochrane Collaboration, Getting Involved
• Campbell Collaboration, Co-ordinating Groups

Adapted from:   https://libguides.bodleian.ox.ac.uk/systematic-reviews/methodology

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Engineering (Basic)

• Getting Started
• Where to Find ...
• Academic Integrity

What is PICO?

Asking the searchable question, searching the answerable question.

• How to Research a Topic
• How to Find Facts, Formulas & Data
• Articles (Journals & Magazines)
• Encyclopedias and Dictionaries
• Advanced Guides

P = Population, Problem, Process

The population doesn't need to be human. In engineering, it is most often a problem or process.

I = Intervention, Inquiry, Investigation, Improvement

Possible solution

C = Comparison

Current practice or opposing viewpoints

O = Outcomes

Measuring what worked best

PICO Question | Engineering

Background | five ws.

Who or What           equals               Population, Problem or Process

How or Why            equals               Intervention, Investigation or Improvement

When                      equals               Special conditions

Example:   How can PV cells be made more efficient, especially in low sun conditions?

Ask broad topical question and read to: build knowledge base. identify trending facts, issues, cutting edge research lay foundation for asking focused research question

Foreground | PICO

Example:    In  PV cells  (P) how does using  gallium  (I) compared to silicon (C) improve  electrical production efficiency (O)?

Formulate research question using PICO to: identify research elements related to topic select keywords representing those elements retrieve relevant research articles when PICO keywords appear in TI,AB

Search in Compendex & Inspec :

SS1: ( PV or photovoltaic)  AND (gallium OR silicon) AND efficien*

SS2: ((((PV or photovoltaic) WN TI) AND ((gallium OR silicon) WN TI)) AND ((efficien*) WN TI)) 

Search in Academic Search Premier :

SS1: (PV or photovoltaic) AND (gallium OR silicon) AND efficien*

SS2: TI (PV or photovoltaic) AND TI (gallium OR silicon) AND TI efficien*

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• Last updated: Jan 2, 2024 8:27 AM
• URL: https://libguides.asu.edu/engineering

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• v.106(4); 2018 Oct

The impact of patient, intervention, comparison, outcome (PICO) as a search strategy tool on literature search quality: a systematic review

Associated data.

This review aimed to determine if the use of the patient, intervention, comparison, outcome (PICO) model as a search strategy tool affects the quality of a literature search.

A comprehensive literature search was conducted in PubMed, Embase, CINAHL, PsycINFO, Cochrane Library, Web of Science, Library and Information Science Abstracts (LISA), Scopus, and the National Library of Medicine (NLM) catalog up until January 9, 2017. Reference lists were scrutinized, and citation searches were performed on the included studies. The primary outcome was the quality of literature searches and the secondary outcome was time spent on the literature search when the PICO model was used as a search strategy tool, compared to the use of another conceptualizing tool or unguided searching.

A total of 2,163 records were identified, and after removal of duplicates and initial screening, 22 full-text articles were assessed. Of these, 19 studies were excluded and 3 studies were included, data were extracted, risk of bias was assessed, and a qualitative analysis was conducted. The included studies compared PICO to the PIC truncation or links to related articles in PubMed, PICOS, and sample, phenomenon of interest, design, evaluation, research type (SPIDER). One study compared PICO to unguided searching. Due to differences in intervention, no quantitative analysis was performed.

Conclusions

Only few studies exist that assess the effect of the PICO model vis-a-vis other available models or even vis-a-vis the use of no model. Before implications for current practice can be drawn, well-designed studies are needed to evaluate the role of the tool used to devise a search strategy.

INTRODUCTION

The development of systematic reviews is considered a means of enabling clinicians to use evidence-based medicine (EBM) [ 1 ], and the number of systematic reviews is growing quickly [ 2 ]. As literature searching forms the underlying basis of systematic reviews, the quality of the literature search is crucially important to the overall quality of the systematic review [ 3 ]. Although new techniques can automate the process of systematic reviews, such as using text mining to develop search strategies [ 4 ], the task of devising the search strategy still requires intellectual contributions from reviewers. In particular, as the search strategy builds upon the review question, formulating the review question is critical to developing the search strategy.

In their 1992 publication in the Journal of the American Medical Association, the Evidence-Based Medicine Working Group emphasized the precise definition of the patient problem, the required information needed to resolve the problem, and the ability to conduct an efficient search as the skills required for practicing EBM [ 5 ]. In addition to these skills, the use of conceptualizing models to structure a clinical question was introduced in 1995, when Richardson et al. proposed the use of a four-part model to facilitate searching for a precise answer [ 6 ]. They stated that a clinical question must be focused and well articulated for all four parts of its “anatomy”: the patient or problem (P); the intervention or exposure (I); the comparison intervention or exposure (C), if relevant; and the clinical outcome of interest (O).

Despite the existence of other models—such as sample, phenomenon of interest, design, evaluation, research type (SPIDER) [ 7 ] and setting, perspective, intervention, comparison, evaluation (SPICE) [ 8 ]—the PICO model is by far the most widely used model for formulating clinical questions. The purpose of using PICO is considered to be three-fold [ 9 ]. First, it forces the questioner to focus on what the patient or client believes to be the single most important issue and outcome. Second, it facilitates the next step in the process—the computerized search—by prompting the questioner to select language or key terms to be used in the search. Third, it directs the questioner to clearly identify the problem, intervention, and outcomes related to specific care provided to a patient.

The PICO model is also frequently used as a tool for structuring clinical research questions in connection with evidence syntheses (e.g., systematic reviews). The Cochrane Handbook for Systematic Reviews of Interventions specifies using PICO as a model for developing a review question, thus ensuring that the relevant components of the question are well defined [ 10 ]. The PICO framework is primarily centered on therapy questions, and although it can be adapted to formulate research questions related to prognosis or diagnosis, it is less suitable for other types of clinical information needs [ 11 ].

In addition to acting as a conceptualizing tool for asking clinical and research questions, the PICO model can be used as a tool for developing search strategies. According to Considine et al., “the PICO Framework should also be used to develop the search terms that are informed by the PICO question, Medical Subject Headings (MeSH) and any other terms deemed to be relevant” [ 12 ]. For a default search, the Cochrane Handbook suggests employing only search terms for patients, the intervention, and the study type [ 13 ], thus reducing the PICO model to P, I, and S/T (i.e., study type or types of study). Alternatively, instead of study type or types of study, the truncated PIC approach emphasizes the comparison intervention or exposure.

Although conceptualizing models are widely used by information specialists, little is known about the impact of using them as tools for developing search strategies. Therefore, the aim of this systematic review was to determine whether the use of the PICO model as a search strategy tool improves the quality of literature searches.

This systematic review was conducted and reported according to quality standards described in the AMSTAR measurement tool [ 14 ] and the PRISMA 2009 checklist [ 15 ]. Two reviewers independently carried out study selection, evaluation, and data extraction. We resolved discrepancies in our reviews by consensus. Covidence systematic review software (Veritas Health Innovation, Melbourne, Australia) was used to screen, select, and extract data from included studies. The review protocol was registered in the PROSPERO database (CRD42017055217).

Search strategy

We searched PubMed ( Table 1 ), Embase, CINAHL, PsycINFO, the Cochrane Library, Web of Science, Library and Information Science Abstracts (LISA), Scopus, and the National Library of Medicine catalog on January 9, 2017. After testing and validating our PubMed search strategy using the capture-recapture technique as well as evaluating retrieval of known items [ 16 ], we translated the search strategy for use in other databases, adjusting the controlled vocabulary as applicable ( supplementary Appendix A ). We also examined reference lists and performed citation searching (Web of Science, v.5.23.2, up to February 1, 2017) of included studies to identify other potentially relevant studies.

PubMed search strategy

Inclusion and exclusion criteria

We considered all primary studies, regardless of design, as eligible for inclusion if they examined PICO as a tool for developing a search strategy (distinct from other methods for developing a search strategy) for identifying potentially relevant studies in any topic area. We excluded review articles but examined their reference lists to identify other potentially relevant studies. We applied no other restrictions, such as those related to languages or publication years, in this review.

Outcome measures

Our primary outcome measure was the quality of literature searches using two measures: precision and sensitivity [ 17 ]. The Cochrane Handbook defines sensitivity as the number of relevant reports found divided by the total number of relevant reports in existence and precision as the number of relevant reports found divided by the total number of reports identified [ 10 ]. Our secondary outcome measure was time spent on the literature search.

Data extraction

We noted and summarized information pertaining to author, year of publication, study design, searchers, search strategy tools, and calculation of sensitivity and precision. Studies that did not evaluate and quantify the quality of the literature searches in terms of both precision and sensitivity were excluded from analysis. Empirical studies show that recall and precision are inversely related. High recall can easily be obtained but will, however, be at the expense of precision. Because a trade-off between recall and precision is unavoidable, one should only evaluate searches with both of these measures [ 18 ].

Risk of bias assessment

No validated criteria exist for assessing the risk of bias in studies evaluating the effect of PICO as a tool for developing the search strategy in terms of the quality of the searches. Therefore, we used a self-developed set of three criteria: (i) searcher skills, (ii) match between model and question, and (iii) performed searches ( Table 2 ). Each criterion consisted of a set of individual considerations and was assessed using the categories “low risk of bias,” “high risk of bias,” and “unclear risk of bias.” If one of the considerations in a criterion was judged as “high risk of bias” or “unclear risk of bias,” the overall judgment for that criterion was “high risk of bias” or “unclear risk of bias,” respectively. We developed the three criteria by consensus; however, this tool was not validated.

Risk-of-bias criteria

(i) Searcher skills

The searchers (i.e., study participants or authors) were the individuals performing the literature searches. If the searchers differed in their searching skills, this might have affected the overall results of the study. Thus, if some searchers had more training in literature searching than others, this could introduce a risk of bias. Similarly, if some of the searchers were familiar with the search strategy tools prior to the study, this also increases the risk of bias. Furthermore, if searchers used all included models in the study (e.g., were instructed to use particular conceptualizing models or unguided searching), the order in which the search strategy tools were applied might have affected search behavior, thus, introducing a risk of bias. Finally, although blinding of the searchers is not possible, blinding of the reviewers evaluating the search results is possible and serves to reduce the risk of bias resulting from knowing the identity of the searchers or search strategy tools that were applied.

(ii) Match between model and question

Our risk-of-bias assessment for this criterion was based on the consideration that particular conceptualizing models might be developed to fit different topics or quantitative versus qualitative research and might apply to some topics or research areas better than others, which could influence the study results. Recent recommendations show that different review types require different question formats (i.e., different conceptualizing models and, thus, different search strategy tools) [ 19 ]. The fit between model and topic cannot be manipulated (e.g., if a research question does not include an intervention, all elements of the PICO model will not be applicable and, thus, will not fit that particular research question). We considered applying a conceptualizing model that was not fit for that particular research area a high risk of bias.

Another aspect of the fit between model and question is the relevance of the obtained search results. As sensitivity and precision measures are based on relevance, the search results need to be assessed for their relevance. Determination of the relevance of the obtained search results is performed ideally using a predefined set of publications (i.e., a gold standard), such as those retrieved in a systematic review, that can serve to assess the relevance of the search results. Alternatively, an expert group could assess the relevance of the retrieved results. A system’s view of relevance (i.e., the ranking of results or a study being present in the search results) is not sufficient [ 20 ]. We considered applying precision and recall without considering relevance based on a gold standard or an expert group a high risk of bias.

Finally, the number of search elements or search blocks needs to be considered, regardless of whether the search was unguided or structured by the use of a search strategy tool. All other things being equal, the number of retrieved articles will decrease as the number of blocks is increased. Consequently, the more elements, the fewer hits, which would affect the results of the study in terms of comparing applied search strategy tools. We considered search strategy tools (i.e., conceptualizing model or unguided search) that had a different number of search elements or search blocks a high risk of bias.

(iii) Quality of searches

Our risk-of-bias assessment for this criterion was based on our consideration that the quality of the literature searches might impact the results of the study. Searches could be consistently high quality or consistently low quality, which does not in itself imply high risk of bias. However, if the quality of the searches is not consistently high or low, bias can occur. The quality of searches in this case was determined using criteria outlined in the PRESS statement [ 3 ], stressing that the criteria and methods depended on the specific databases. If the literature search was not conducted uniformly or if subject headings were not correctly adapted for each database, we considered it to have a high risk of bias.

Due to differences in the comparisons among search strategy tools in the included studies, we did not perform quantitative analyses. We, therefore, did not follow the sections in the PRISMA 2009 checklist [ 15 ] that relate to meta-analysis.

The literature search identified a total of 1,269 unique records ( Figure 1 ). We assessed 22 full-text articles for eligibility and excluded 19 due to wrong study design (i.e., studies that did not examine PICO as a tool for developing a search strategy for identifying potentially relevant studies in any topic area), wrong outcomes, or wrong interventions ( supplementary Appendix B ). Therefore, three studies were included in the qualitative analysis [ 21 – 23 ] ( Table 3 ).

Study selection flow diagram

Use of the patient, intervention, comparison, outcome (PICO) model compared to another conceptualizing model as a literature search strategy tool

* Queries were combined with a †broad therapeutic intervention filter, ‡a narrow therapeutic intervention filter, or §no filter and further limited to **English language and human studies; ††English language, human studies, and Abridged Index Medicus titles; or ‡‡no limitations.

Agoritsas et al. evaluated searches outlined by the authors of the study based on the PICO framework and combined into queries; although not explicitly stated, the authors likely also performed the searches [ 21 ]. The study evaluated 15 search strategies that varied in their query structure (PIC or PICO), use of PubMed’s Clinical Queries therapeutic filters (broad or narrow), and search limits, as well use of PubMed links to related articles. A total of 450 searches were performed. Relevance was assessed on the first 40 records of the search output as well as the complete search output. The study reports that the PICO model resulted in increased median sensitivity and precision of the search results.

Hoogendam et al. evaluated the effectiveness of PICO versus unguided searching among 14 residents and 8 specialists who had an interest in vascular medicine [ 22 ]. Participants received a lecture by an expert searcher explaining the basics of PubMed to ensure a basic knowledge of PubMed functionality. Participants performed unguided searching for 5 minutes on 12 therapeutic questions regarding vascular medicine. After 2 weeks, an expert searcher explained the use of PICO, and participants performed PICO searching for 5 minutes on 12 different therapeutic questions. Although not statistically significant at the p <0.05 level, using the PICO model resulted in a higher average sensitivity and lower average precision than did unguided searching.

Methley et al. evaluated the SPIDER conceptualizing model [ 23 ]. The authors developed a detailed search strategy in collaboration with a specialist librarian and information specialist. Identical search terms were combined using the PICO, PICOS, or SPIDER search strategy tools and compared across PubMed, Embase, and CINAHL, resulting in a total of nine searches. The authors found that PICO retrieved the largest number of hits and recommended using PICO instead of SPIDER.

Qualitative analysis

The three included studies varied widely in their design, choice of comparators, number of databases searched, procedure for relevance assessment, and methods of calculating outcomes ( Table 3 ).

Study design

One study was designed as a randomized trial including health professionals (residents and specialists) [ 22 ]; the other two were observational studies in which the authors were involved in the literature searches along with a specialist librarian and information specialist [ 23 ] or without stating who exactly performed the searches [ 21 ].

Relevance assessment

Two of the three included studies used Cochrane systematic reviews to formulate the clinical questions. These reviews were used as a basis for the search strategies and as a gold standard for determining the sensitivity and precision of the search results [ 21 , 22 ]. One study compared PICO to PICOS and SPIDER with a focus on a specific research question; as a consequence, the search strategy was built from elements of the research question, and the relevance of search results was judged against inclusion criteria [ 23 ]. Consequently, the included studies calculated sensitivity and precision from a gold standard [ 21 , 22 ] or a list of included studies [ 23 ].

Choice of comparator

Two of the three included studies compared the PICO model to alternative conceptualizing models. However, the two studies compared PICO to different conceptualizing models; thus, the PICO model was not compared to the same alternative conceptualizing models across studies.

One study compared the PICO model to the truncated PIC model in PubMed and reported that the PICO model resulted in increased median sensitivity and precision of the searches [ 21 ]. However, the performance of the tested search strategies was highly variable depending on the clinical question, and none of the 15 strategies showed a consistently high sensitivity in retrieving relevant articles. The study also used PubMed links to related articles as a search strategy, which resulted in higher sensitivity and precision than both the PICO and PIC models. The calculations were based on the first 40 records of the PubMed output as well as the complete search output. When the full output was screened for relevant studies, about 85% of records were detected by the PIC queries and about 69% by the PICO queries [ 21 ].

One study compared the PICO model to PICOS and SPIDER in CINAHL, Embase, and MEDLINE [ 23 ]. Although hardly conclusive due to extremely limited data, the use of PICO as a search strategy tool resulted in higher sensitivity and lower precision than the use of PICOS and SPIDER. However, as different numbers of search blocks were used for each model (i.e., PICO: 3 search blocks, PICOS: 4 search blocks, SPIDER: 6 search blocks), these results are expected.

One study compared the PICO model to unguided searching [ 22 ]. The study reported that use of the PICO model resulted in higher average sensitivity and lower average precision than did unguided searches, although this difference was not statistically significant.

Outcomes reported

None of the included studies investigated the time spent on the literature search.

We used three risk-of-bias criteria to assess the risk of bias: (i) searcher skills, (ii) match between model and question, and (iii) quality of searches. Overall, there were several instances of unclear or high risk of bias with respect to all three criteria ( Table 4 ). The searcher skills criterion revealed either an unclear risk of bias [ 21 , 23 ] or a high risk of bias [ 22 ] in the studies. The match between model and question criterion revealed that two studies [ 21 , 23 ] had a high risk of bias and one study [ 22 ] had an unclear risk of bias. Finally, we found that the quality of searches criterion revealed that two studies [ 21 , 22 ] had an unclear risk of bias, and one study had a low risk of bias [ 23 ]. A complete overview of the risk of bias assessments can be found in supplementary Appendix C .

Risk-of-bias summary

This study is the first systematic review aiming to determine whether the use of the PICO model as search strategy tool affects the quality of the literature search, which had the potential to provide valuable evidence of the effect of using PICO to formulate search queries. This review is strengthened by the use of rigorous methods based on prespecified criteria in a protocol following both the AMSTAR measurement tool [ 14 ] and PRISMA 2009 checklist [ 15 ], a comprehensive literature search and duplicate screening process, data extraction, and risk-of-bias assessment. However, we identified only three studies that were eligible for inclusion in the review [ 21 – 23 ], and given the marked differences among studies, it was only possible to perform qualitative analysis.

Despite the rigorous methodology that we used, there are limitations for this review. No validated assessment tool exists for these types of studies, which led us to develop our own set of risk-of-bias criteria. As opposed to validated criteria such as Cochrane’s risk-of-bias tool for assessing randomized trials [ 24 ], our tool was not validated, which would have been preferable. Despite the limitations of our risk-of-bias tool, we regarded all three included studies [ 21 – 23 ] as having a high or unclear risk of bias. Consequently, it is extremely difficult to draw any conclusions from their findings.

As no similar reviews exist, we turn to the individual studies to enlighten our discussion on whether the use of the PICO model as search strategy tool affects the quality of the literature search. Two issues are prominent: the importance of the number of search blocks and the practice of avoiding outcome-related terms in the search strategy.

First, the number of search blocks in a literature search is important for the search output. That is, the more search blocks that are included, the more restricted the search output will be. One of the included studies did not compensate for the number of search blocks in each strategy, and thus, as expected, the search strategy tool with the lowest number of blocks retrieved a greater number of hits [ 23 ]. Existing guidelines recommend using only the truncated PIC version of the PICO model for performing literature searches for systematic reviews [ 13 ]. The rationale is that some or all outcome measures might not be mentioned in abstracts, and including a search block defining the outcomes leads to a lower sensitivity of the literature search.

One study that was included in this review investigated the median sensitivity and precision of the PICO model compared to the PIC model [ 21 ]. Surprisingly, the study reported that the PICO model performed better than the truncated PIC model with regard to sensitivity and precision. However, these results were based only on the first forty records of the search output, which might explain this surprising finding, because an inverse relationship usually exists between sensitivity and precision [ 18 ]. Also, depending on how the search results were sorted, different results could be obtained. When considering the full search output, the PIC model did show a higher sensitivity and lower precision, although both measures varied greatly across different searches [ 21 ]. This finding of higher sensitivity and lower precision when using the PIC model (three search blocks) compared with the PICO model (four search blocks) [ 21 ] is in accordance with another included study that found that the PICO model (using three search blocks: P, I, and O) resulted in higher sensitivity and lower precision than the PICOS model (four search blocks) or SPIDER model (five search blocks) [ 23 ]. Taken together, these results suggest that the number of search blocks impacts the quality of the search output as quantified by sensitivity and precision.

Second, the claim that searching for outcome-related terms when using the PICO model as a search strategy tool lowers the sensitivity of the search [ 13 ] is not substantiated. Based on the limited data from this review, however, we are not able to make any firm conclusions. The study addressing this issue [ 21 ] focused on identifying search components and tools that could help clinicians build more effective strategies to answer questions at the point of care and did not include sophisticated strategies used for performing systematic reviews; thus, its results are of limited generalizability. Future studies investigating the effect of searching for outcome-related terms are needed to support this recommendation [ 10 ].

The PICO model was developed to help structure a well-built clinical question and enable a literature search [ 6 ]. Since its introduction, it has played an important role as a conceptualizing model in EBM [ 10 ]. However, evidence of the effect of using the PICO model as a search strategy tool is still lacking, and the studies that were included in this review do not allow us to build upon this important body of evidence. To practice EBM with evidence-based methods, and thus ensure rigorous methodology, the results of this review indicate that more work is needed to assess the applicability of specific conceptualizing models. Furthermore, we propose that it is important for future research on this topic to address three potential risks of bias: (i) searcher skills, (ii) match between model and question, and (iii) quality of searches.

Overall, there have been few studies assessing the effect of using the PICO model versus other available models or unguided searching on the quality of literature search results. Specifically, despite a rigorous search and selection process, we found only three such studies. Due to heterogeneity among these studies, quantitative analysis was not possible, and no solid conclusions about the effect of using the PICO model on the quality of the literature search could be drawn. Before implications for current practice can be made, there is a need for well-designed studies to evaluate the role of the tool used to devise a search strategy.

SUPPLEMENTAL FILES

Acknowledgments.

We thank the anonymous referees for their useful suggestions and Rasmus Højbjerg Jacobsen for carefully revising the manuscript.