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Searching the Literature: A Guide to Comprehensive Searching in the Health Sciences

Students and researchers in the health sciences are often required to conduct comprehensive searches of the literature. Follow the steps in this guide to learn how this process works.

Turn your Research Question into a Searchable Question

A clearly-defined question will: 

  • focus your search so that it is more efficient and effective
  • make searching for evidence simpler as a well-formed question makes it easier to find and combine appropriate terms
  • help you identify relevant results and separate relevant results from irrelevant ones


Example of a vague question
Does psychotherapy work in patients with depression so they can resume normal daily activities?

Problems with this question:

  • Psychotherapy is a very broad term.  There are many (over 50) different types of psychotherapy treatments. Do you mean any and all of them?  Do you mean a specific type of therapy such as dance therapy or gestalt therapy?
  • What does "work" mean?  How will you determine if the therapy has worked?  When the patient no longer needs the therapy anymore?
  • Who are these patients?  Adults? Adolescents? Men? Women? Outpatients?
  • Depression is also a very broad term.  What type of depression - post partum?  All types of depression? 
  • What does normal daily activities really mean?  Return to work?  Engage in social situations? Take up a hobby?
  • What time frame are you looking at?  Therapy which last one year? Two years? Three months?


Example of a focused question
Does cognitive behaviour therapy in comparison to treatment-as-usual improve depressive symptoms in adult patients with major depressive disorder so they can return to work after three months of the treatment start time?


Some common ways to define and focus your question is to use PICO or concept mapping.

Classic Question Formulas

1. PICO(T)

PICOT is a tool for distilling the essential components of a research topic into concepts. Finding relevant medical information is often easier if you break down your research topic  by developing a PICOT question. PICOT is an acronym for:
Patient / Population / Problem: How would you describe this group of patients similar to yours? What are the most important characteristics of the patient(s)? what sorts of participants, from where, with what features? What is the health problem you are investigating? 
Intervention: the treatment, drug, or technology; what is the exposure? What dose? 
Comparison: What is the main alternative to compare with the intervention? At times your question may not have a comparison!
OutcomeWhat are you aiming to accomplish, measure, improve, make an impact on? Are you trying to eliminate or relieve symptoms? Reduce the number or severity of adverse effects? Improve functions?
Type of studyDepending on your question, you might also include a fifth line on Type of Method/Study, in which you would specify the type of study you will look at.Sometimes T stands for time factors - 1 year after? 3 months?


EXAMPLE: Does exercise in comparison with diet reduce the incidence of people with heat disease from experiencing a heart attack?

Patient or Population: People with heart disease, ie. who have had a cardiac event

Intervention: Moderate exercise

Comparison: Dietary changes, medications

Outcome: Reduction in incidence of heart attacks and mortality rates from heart disease

Notice how this structure forces the researcher to be more specific. With an example like this one, you would also want to clearly define each term.


2. PIE

Like PICO, it is a way to focus a topic into a targeted research question. PIE is better suited for qualitative research questions. PIE is an acronym for: 
Patient / Population / Problem: How would you describe this group of patients similar to yours? What are the most important characteristics of the patient(s)?             
Intervention / Issue: Which is the main prognostic factor, intervention, treatment, or exposure you are considering? What do you want to do for the patient? What other factors can influence the prognosis?
Evaluation / Effect (method): What methods are being used or most appropiate to evaluate the outcome? Clinical queries? Trials? Focus groups? What are you trying to measure?

Another way to identify searchable components in your question: Concept Mapping


Some questions do not fit PICO. For instance, a systematic review on the cost-effectiveness of interventions for a disease may not have a simple outcome in mind.

Some people find brainstorming techniques such as concept mapping more helpful.Breaking the question down into concepts and thinking of different ways of saying or describing each concept.

For example: I would like to explore the factors affecting compliance with a methadone maintenance program for my patients with heroin addiction issues. Why do so many patients drop out or refuse to be treated in the first place? 







Concept and synonyms


Heroin addiction



Methadone maintenance





Treatment refusal



Questionnaires OR

Focus groups


Search question becomes: What factors affect compliance in a methadone maintenance program for patients with heroin addiction issues?