How to find evidence

We are constantly bombarded with information from a wide range of sources. Traditional sources of information (books, journals and colleagues) as with other sources have their limitations.

With the rise of the internet, an increasing number of electronic databases are available which can provide access to the best current evidence. The most widely available free database is Medline which can be accessed via the PubMed interface. Increasingly databases are providing explict evidence; a good example is the Evidence-based Medicine reviews product from Ovid, which combines a number of electronic databases (Cochrane Database of Systematic Reviews, Best Evidence, Evidence-based Mental Health and Evidence-based Nursing, Cancerlit, Healthstar, Aidsline, Bioethicsline and Medline). Academic institutions and NHS staff (with an ATHENS Password) have access to these services which normally require subscriptions.

Knowledge is of two kinds. We know a subject ourselves, or we know where we can find information on it.
Samuel Johnson (1709 – 1784)

The Cochrane Library is  a collection of databases that contain different types of high-quality, independent evidence to inform healthcare decision-making.:

  • The Cochrane Database of Systematic Reviews
  • The Cochrane Central Register of Controlled Trials (CENTRAL)
  • Cochrane Clinical Answers

The Cochrane Library is probably the best single source of reliable evidence about the effects of healthcare.

Structured approach to searching

In order to be really effective in searching for evidence, specific training or access to an information specialist is required. However for a busy practitioner a quick structured approach is

  • First define the question – then search for each of the following in turn
    • Evidence-based Guidelines
    • Cochrane Reviews
    • Evidence summaries (e.g from Specialist Library for Oral Health)
    • Medline – for appropriate studies to answer your question

Relevant Links


Papers on searching from the Canadian Dental Journal series on Evidence-based Dentistry

Search filters


Search Engines

  • Epistemonikos – a collaborative, multilingual database of health evidence. It is the largest source of systematic reviews relevant for health-decision making, and a large source of other types of scientific evidence.
  • NICE Evidence – National Institute for Health and Care Excellence
  • SUMSearch  medical meta-search engine which searches a range of databases and  internet site
  • TRIP Turning Research into Practice  Excellent UK based meta-search engine