Evidence Based Research
It's important to ask a question that can be answered through use of evidence rather than subjective judgment. Evidence-based medicine (EBM) - like evidence-based practice in any discipline - draws on empirical evidence. This may include laboratory studies, clinical trials, and real-world prospective or retrospective studies. You may need to rephrase the question according to whether the evidence base is in diagnosis, therapy & interventions, prognosis, or assessments of harm.
EBM gives more weight and authority to randomised controlled clinical trials and cohort studies than case studies. It gives more weight again to meta-analyses synthesising the results of many RCTs.
Figure 1: The hierarchy of evidence
Greenhalgh (1997) gives an alternative ranking of the types of primary study :
(1) Systematic reviews and meta-analyses
(2) Randomised controlled trials with definitive results (confidence intervals that do not overlap the threshold
clinically significant effect)
(3) Randomised controlled trials with non-definitive results (a point estimate that suggests a clinically
significant effect but with confidence intervals overlapping the threshold for this effect)
(4) Cohort studies
(5) Case-control studies
(6) Cross sectional surveys
(7) Case reports.
Evidence Based Databases
- Cochrane Library (Wiley)The Cochrane Library is a collection of six databases that contain different types of high-quality, independent evidence to inform healthcare decision-making, and a seventh database that provides information about groups in The Cochrane Collaboration. They are the Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, Cochrane Methodology Register, Database of Abstracts of Reviews of Effects, Health Technology Assessment Database, NHS Economic Evaluation Database, and About The Cochrane Collaboration.
- Joanna Briggs Institute(JBI COnNECT+) Clinical Online Network of Evidence for Care and Therapeutics.
- PubMed Clinical Queries (NCBI) This link opens in a new windowSystematic reviews, clinical studies and medical genetics are extrapolated from the PubMed platform.
- BMJ Best PracticeBMJ Best Practice is a easy-to-use decision-support tool that provides authoritative answers to clinical questions. It contains information relating to over 10,000 diagnoses, more than 3,000 diagnostic tests and over 4,000 diagnostic and treatment guidelines. At its core, Best Practice contains the internationally renowned Clinical Evidence. Drug information is provided by Martindale: the Complete Drug Reference. Martindale can be accessed via the Drugs menu or by selecting a drug when viewing a condition or symptom.
Evidence Based Resources
