Clinical Guides: Literature Searching: Formulating a Research Question

Before hitting the databases, you should plan your search strategy. Planning will help you gain an understanding of your research topic, which will inform your research question, the direction you want to take, and the key concepts that you want to focus on. Without careful planning your search could become disjointed, and you may miss important papers.

Formulating an answerable question

A clear clinical question with define your information need, identify search concepts, and help you select appropriate resources to search.

The PICO acronym helps structure your clinical question to ensure that it is answerable. This makes it easier to locate the most appropriate evidence for your situation and reduces the risk of concepts being left out. PICO is widely used in professional practice and strongly advocated as a tool in the national health standards. Being as detailed and explicit as possible will help you create a PICO framework that is both focused and comprehensive.

PICO's meaning is best explained by its four key elements, which are:

Note: the PICO framework is best suited to questions of clinical effectiveness. If your research question is focused on experiential data, cost-effectiveness, or something else, click the "PICO alternatives" tab to view alternative frameworks.

PICO Examples

Clinical examples using PICO

How to create PICO questions about diagnostic tests

PICO Variations

In PICOT, the 'T' is for a specified time period, e.g. "over 5 years" or "24 hours after surgery". It can also be a type of study -- e.g. qualitative study -- or test.

Here, the 'S' stands for study type or study design. Depending on your question, certain study types may be more appropriate clinical evidence than others. E.g. RCTs for therapy questions

The 'C' is for context (or place), e.g. "the ED", "teaching hospitals", or "high-income countries".

It is important to fill knowledge gaps before you start developing a search strategy. This can help:

Clarify definitions
Investigate concepts you may not fully understand
Identify keywords and phrases associated with your topic
Scope out existing literature

Background searching can be done using a variety of sources.

The Library catalogue is a good place to start looking for background information such as:

Textbooks
Encyclopaedias
Dictionaries

Library Catalogue

Clinical support tools such as UpToDate, BMJ Best Practice, and the Australian Medicines Handbook are good for background information on clinical queries. Visit the Library website for a full list of clinical support tools and information on how to access them onsite and remotely.

Clinical Support Tools

Qualitative Research

These frameworks may be more appropriate for qualitative questions, such as those investigating experiences or perspectives.

PICo
P = Population
I = phenomenon of Interest
Co = Context

SPIDER
S = Sample
PI = Phenomenon of Interest
D = Design
E = Evaluation
R = Research type

SPICE
S = Setting
P = Perspective
I = Intervention
C = Comparison
E = Evaluation

Etiology and/or Risk

The PEO framework is designed for questions looking at the association between risk factors (or exposures) and outcomes.

PEO
P = Population
E = Exposure (independent variable)
O = Outcome (dependent variable)

Prevalence or Incidence

To search for studies on the prevalence or incidence of a given condition, use the memorably named CoCoPop framework.

CoCoPop
Co = Condition
Co = Context
Pop = Population

Diagnostic Test Accuracy

If you are searching specifically for studies relating to diagnostic test accuracy, you can use the PIRD framework.

PIRD
P = Population
I = Index test
R = Reference test
D = Diagnosis of interest

To learn more about searching for studies of diagnostic test accuracy, see the JBI Manual for Evidence Synthesis. The manual is designed for those undertaking a systematic review or other evidence synthesis work, however the general principles can be applied to any literature search.

JBI Manual for Evidence Synthesis

Other Research Questions

The below frameworks may be more suitable for questions relating to service improvement, cost-effectiveness, or similar.

ECLIPS

E = Expectation
C = Client group
L = Location
I = Impact
P = Professional(s)
S = Service

CLIP

C = Client
L = Location
I = Improvement
P = Professional(s)

For more information on alternative question frameworks including examples, visit the guide below from the University of London.

University of London - Question Framework Guide

After developing a clear research question, consider whether your search will be more sensitive or more precise. Read on to learn more about the differences between each approach and the practical implications for your search process.

What does sensitivity vs. precision mean?

Put very simply, these terms equate to the size of the 'net' that you use to 'catch' relevant literature during your search.

The more sensitive your search, the bigger your net. The more precise your search, the smaller your net.

Sensitive search

Definition	A comprehensive search that retrieves the maximum amount of relevant studies, but which requires additional time and resources for filtering and screening results. As sensitivity increases, so does the number of results. A highly sensitive search casts a wide net and therefore has lower precision.
Usage	Literature reviews Systematic reviews Meta-analyses Searches/questions that require thoroughness and there is time set aside to screen and analyse the search results Multifaceted clinical queries with broad and complex concepts, such as, "What practices prevent transmission of infections from the hospital environment onto healthcare workers' clothing and the personal items they bring to work?"
Tips	Spend as much time as possible in the planning phase. Ensure you combine subject headings with keywords. Add synonyms for each of your key concepts. Only apply limits if they can be fully justified. Search multiple databases and grey literature. Check the indexed terms for your 'gold set' articles (6-10 articles that are most relevant) and add these to your search. Conduct hand searching and reference checking.

Definition

A comprehensive search that retrieves the maximum amount of relevant studies, but which requires additional time and resources for filtering and screening results. As sensitivity increases, so does the number of results.

A highly sensitive search casts a wide net and therefore has lower precision.

Usage

Literature reviews
Systematic reviews
Meta-analyses
Searches/questions that require thoroughness and there is time set aside to screen and analyse the search results
Multifaceted clinical queries with broad and complex concepts, such as, "What practices prevent transmission of infections from the hospital environment onto healthcare workers' clothing and the personal items they bring to work?"

Tips

Spend as much time as possible in the planning phase.
Ensure you combine subject headings with keywords.
Add synonyms for each of your key concepts.
Only apply limits if they can be fully justified.
Search multiple databases and grey literature.
Check the indexed terms for your 'gold set' articles (6-10 articles that are most relevant) and add these to your search.
Conduct hand searching and reference checking.

Precise search

Definition	A targeted search that captures the most relevant studies, but does not necessarily locate every single piece of relevant literature. A highly precise search risks missing relevant studies -- as it casts a small net -- but this approach is still suitable in many situations.
Usage	Clear questions with singular, simple concepts. For example, "What is the recommended dosage of paracetamol for a child with fever?" When looking for a recent review on a specific condition or topic To locate a couple of key articles to stimulate further discussion in a journal club
Tips	Tightly refine your question to ensure it is direct and focused. Add synonyms judiciously. Restrict keywords to the fields for title, abstract, and author provided keywords (e.g. .tw. in Medline). Use database tools that restrict results to studies containing your search terms as the main subjects only (e.g. focus in Medline). Add limits such as the last 5 years and/or certain levels of evidence.

Definition

A targeted search that captures the most relevant studies, but does not necessarily locate every single piece of relevant literature.

A highly precise search risks missing relevant studies -- as it casts a small net -- but this approach is still suitable in many situations.

Usage

Clear questions with singular, simple concepts. For example, "What is the recommended dosage of paracetamol for a child with fever?"
When looking for a recent review on a specific condition or topic
To locate a couple of key articles to stimulate further discussion in a journal club

Tips

Tightly refine your question to ensure it is direct and focused.
Add synonyms judiciously.
Restrict keywords to the fields for title, abstract, and author provided keywords (e.g. .tw. in Medline).
Use database tools that restrict results to studies containing your search terms as the main subjects only (e.g. focus in Medline).
Add limits such as the last 5 years and/or certain levels of evidence.

Which approach is right for you?

An ideal search for your research question will strike an appropriate balance between sensitivity and precision. Although a balance can be achieved, it is impossible to cater for both 100% sensitivity and precision at the same time. You will need to decide which approach to favour based on your question, resources (e.g. time for screening results), and situation.

In practice, the balance between sensitivity and precision is determined by the search question and a researcher’s objectives.

It is useful to build a 'gold set' of relevant references before you develop your search strategy. Also referred to as a 'sample set', a gold set refers to a collection of exemplar articles that are highly relevant to your topic of interest, with sound study design.

How to use a 'gold set'

The papers in your gold set can be used to help identify relevant search terms that can be included in your own search strategy.
As you develop your search, use your gold set to test that your strategy will retrieve the papers in your set, and other relevant references on your topic. This indicates that your search strategy is sound.

How to collect a ‘gold set'?

The papers in your gold set may come from a variety of sources:

Key papers recommended by subject experts, supervisors, or peers
Articles located via reference checking of key papers provided by subject experts or supervisors
Results of preliminary 'scoping searches' from databases such as Medline, Embase, or PubMed
Citation searching to locate further relevant references cited in, or by, key papers. Databases including Scopus and Web of Science, and search engines such as Google Scholar, include information about who cited a particular reference. Look for "Cited by" or "Times Cited" features.