BMJ Clinical Evidence Systematic reviews
BMJ Clinical Evidence provides up to date systematic reviews of the best evidence for over 240 medical conditions across a broad range of clinical specialities. We do this by systematically searching and appraising research literature for appropriate systematic reviews and randomised controlled trials (RCTs) every year.
Our process
If we find a good quality systematic review, such as a Cochrane review, we include it together with:
- RCTs published after the review's search date (subsequent RCTs).
- RCTs the review did not include which we feel are appropriate for inclusion (additional RCTs).
- Other appropriate good quality studies.
When we find multiple systematic reviews we select the best and most up to date for inclusion into BMJ Clinical Evidence, preferring reviews with clearly defined clinical questions and search parameters and those which perform appropriate meta-analyses. If we find no good quality systematic reviews we include the primary studies retrieved by our search and appraisal process.
BMJ Clinical Evidence and Cochrane reviews
The Cochrane Collaboration enjoys an earned reputation for producing high quality systematic reviews. Although we use Cochrane reviews as a valuable resource, our systematic reviews differ from Cochrane reviews in several important ways:
- Systematic reviews may be reviews of primary studies, or alternatively may be reviews of other systematic reviews. While Cochrane reviews focus on primary studies, BMJ Clinical Evidence reviews combines both these elements.
- BMJ Clinical Evidence reviews summarise the best evidence across a condition, rather than focusing on a specific intervention within that condition. In this way our reviews may be described as 'umbrella reviews'.
- Where good evidence is not available we summarise guidelines and provide expert commentary both of which are clearly distinguished from our evidence based content.
- We aim to review our search strategies and update our reviews annually with a new planned systematic search of databases and include continuous updating through BMJ Clinical Evidence Updates.
- We do not usually conduct our own meta-analyses, although we include good quality meta-analyses if available.
BMJ Clinical Evidence and the 5S framework
The 5S pyramid conceived by Brian Haynes is an excellent guide to finding the best evidence for decision making (Haynes RB, In press ACP J Club 2006; Haynes RB, In press EBM 2007). In the hands of a busy clinician, the pyramid can turn into a powerful strategy for efficient evidence searching. Users start by searching products at the top of the pyramid and only proceed to lower levels if their questions remain unanswered.
BMJ Clinical Evidence relates to this pyramid at three levels:
- BMJ Clinical Evidence systematic reviews are 'umbrella reviews' providing summaries of the best evidence for a health topic, and as such are categorised as Summaries by the 5S framework.
- BMJ Clinical Evidence reviews for individual interventions also fit into the Syntheses pyramid level.
- Users of BMJ Clinical Evidence may also view original studies by using BMJ Clinical Evidence Updates at the Studies level of the pyramid.
This applicability across the 5S pyramid allows the BMJ Clinical Evidence reader to obtain a multi-layered understanding of the evidence surrounding any condition in an efficient and pragmatic way.