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 freely available to any UK resident (and a number of other countries) and contains a number of databases:
- The Cochrane Database of Systematic Reviews
- Database of Abstracts of Reviews of Effects (DARE)
- The Cochrane Central Register of Controlled Trials (CENTRAL)
- The Cochrane Database of Methodology Reviews
- The Cochrane Methodology Register
- Health Technology Assessment Database (HTA)
- NHS Economic Evaluation Database (NHS EED)
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
- OCEBM Levels of Evidence – Oxford Centre for Evidence-based Medicine
Papers on searching from the Canadian Dental Journal series on Evidence-based Dentistry
- Part II. Searching for Answers to Clinical Questions: How to Use MEDLINE – Susan E. Sutherland
- Part III. Searching for Answers to Clinical Questions: Finding E-vidence on the Internet – Susan E. Sutherland & Stephanie Walker
- PubMed FAQ– Frequently asked questions about PubMed from NCBI
- Centre for Reviews and Dissemination-(University of York) – databases
- Clinical Trials Register USA
- Cochrane Library
- CORDIS Community Research & Development Information Service – European Research
- Medline (PubMed)
- MetaRegister of Controlled Trials searchable, international database of ongoing trials ( ISRCTN Registry)
- NHS Evidence – The principle aim of the NHS Evidence service is to provide easy access to a comprehensive evidence base for everyone in health and social care.
- 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
- Ovid Medline Tutorial for Dentistry – from Faculty of Dentistry, University of Toronto