Skip to Main Content

Evidence-Based Medicine

Background vs. Foreground Questions

Background questions are needed to acquire basic or general knowledge about a topic. These are the who, what, why, when, where, and how questions. For example: What are the major complications of diabetes? Who should be tested for osteoporosis? When should children get the Varicella vaccine? How do cancer cells grow and spread?  

Foreground questions seek information to help make a clinical decision focused on a particular patient or clinical situation. 


To answer foreground questions, use PICO(T) 

In order to practice evidence-based medicine, you need to be able to formulate a good clinical question. It is helpful to use the PICO(T) format. With PICO(T), you divide your topic into its key concepts, formulate your clinical question, and develop a search strategy. 

- Patient or Problem

I - Intervention, Exposure, or Prognostic Factor

C - Comparison, if any

O - Outcome

T - Type of  Question


PICO (+TT) is a mnemonic used to describe the four elements of a good clinical question. It stands for:

  • Patient or Problem
    • What are the characteristics of the patient?
    • What is the condition or disease you are interested in?
  • Intervention or exposure     
    • Which main intervention, prognostic factor, or exposure are you considering?
  • Comparison
    • What is the alternative to the intervention (e.g. placebo, different drug, surgery)?
  • Outcome
    • What can you hope to accomplish, measure, improve or affect?

To make the search for evidence easier, you may want to add TT to the PICO formula. The T's stand for:

  • Type of question
    • therapy, diagnosis, prognosis, harm/etiology or prevention
  • Type of study
    • Systematic review, rct, cohort study, case control study

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.

Structuring Your Search

Select words from the PICOTT concepts to guide the development of a PubMed search. Remember:

  • Start with key concepts. You do not need to use all the words.
  • Consider alternate word endings, especially for key concepts.
  • Consider synonyms
  • Consider MeSH terms
  • Use an OR to combine synonyms and enclose the set of similar words in parentheses
  • Use an AND to combine concepts

Subject Experts

Profile Photo
Kaitlyn Van Kampen
Clinical Librarian
Joseph Regenstein Library, Room 263
Profile Photo
Deb Werner
Director of Library Research in Medical Education
Joseph Regenstein Library, Room 268
Profile Photo
Holiday Vega
Librarian for Health, Psychology, and Social Work