Primary research

If you can’t find the answer to your clinical question in secondary or pre-appraised resources then it’s time to look for original studies in one or more of the large citation databases available on CIAP, such as:

• MEDLINE
• Embase
• PsycINFO or
• ProQuest

However, searches in citation databases can result in many thousands of citations. With so many articles to choose from, how do you assess which are likely to best answer your question?

Whether a paper is useful or not depends to a large extent on the methodology of the research study. Not all methodology is equal in terms of reliability.

In Module 4, we will look at techniques to critically appraise evidence.

Which study type?

While most clinical questions will be about treatment or interventions, there are other clinical questions such as diagnostic accuracy, aetiology, prognosis, or screening intervention. Each of these questions has their own study type that gives the best evidence. The most reliable evidence comes from those studies that maximise the chance of eliminating bias.

The first step in selecting evidence is to decide what broad field of research your clinical question covers:

Broad areas for clinical questions:

Therapy

testing the efficacy of drug treatments, surgical procedures, alternative methods of service delivery, or other interventions

Diagnosis

demonstrating whether a new diagnostic test is valid (can we trust it?) and reliable (would we get the same results every time?)

Screening

demonstrating the value of tests that can be applied to large populations and that pick up disease at a presymptomatic stage

Prognosis

determining what the likely course or outcome of a disease

Causation

determining whether a factor or agent (e.g. environmental pollution, genetic mutation, exposure to a drug or chemical etc.) is responsible for the development of illness.