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Writing in the Health Sciences: Development of PICO

What is PICO

Practitioners of EBP Research often use the PICO format to help define and answer your research question. 

By organizing a research question using PICO, a researcher can determine specific terms that will help find relevant evidence in professional literature. These terms become the search terms used when searching the databases. 


  • POPULATION: What are the characteristics of this patient population and the problem/ question that is being addressed?
  • INTERVENTION: What is the treatment or course of action typically taken being considered?
  • COMPARISON: What is the alternative (or standard course of action) to the intervention to compare it to?
  • OUTCOME: What is the hoped for accomplishment/ improvement/ or affect for the stated population?

PICO Searches in CINAHL

The following video, illustrates how to create a PICO question and how to employ that in the CINAHL databases. While the video is specific to CINAHL, many of the concepts can be applied to other databases.

Video courtesy of Purdue University Northwest Library (PNL). 

Framing Different Types of Clinical Questions


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)?


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.

Database Filter Options for PICO

  • There are multiple limits in advanced search that can help with population: 
    • Age Groups
    • Sex
    • Human
  • Special Interest Limits
    Options here  might help with any of PICO. Here are a few of the options available: 
    • Gerontological Care
    • Nutrition
    • Pain and Pain Management
  • Try the Clinical Queries limit
    Therapy and prognosis may help with intervention and outcome
    • Therapy - High Sensitivity (broader)
    • Therapy - High Specificity (narrower)
    • Therapy - Best Balanced (balanced between sensitivity and specificity)
    • Prognosis - High Sensitivity (broader)
    • Prognosis - High Specificity (narrower)
    • Prognosis - Best Balanced (balanced between sensitivity and specificity)
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