The second issue of the Cochrane Database of Systematic Reviews (CDSR) for 2011 was published in February but we begin by reflecting briefly on last year, when the CDSR moved from a quarterly to a monthly publication, During 2010, 449 Cochrane reviews were published in full for the first time, and 558 were updated. The evidence in a fifth of these updates changed so substantively that the conclusions of the review had to be revised. The potential future growth of CDSR is also clear from the fact that 632 protocols for ongoing Cochrane reviews were added during the year. CDSR has now passed through the landmark of 4500 full Cochrane reviews since it first appeared in 1995, and should see the 5000th full review within a year.
Issue 2 of 2011 takes us one step closer to that with the addition of another 29 full Cochrane reviews and substantial changes to the conclusions of six existing reviews. A further 43 reviews have been brought up to date. The entire collection is available in full at http://www.TheCochraneLibrary.com. Each of the Cochrane reviews includes information on the methods used, details of the eligible research, results of the included studies and the conclusions of the Cochrane researchers.
The new and updated reviews cover a wide range of health issues and a wide variety of interventions. Among them are several showing the benefits of drugs such as nebulized epinephrine for croup in children (1), levodopa for restless legs syndrome (2) and short- and intermediate-term creatine treatment to improve muscle strength in people with muscular dystrophies (3). Another new review found that adding radiotherapy to chemotherapy improves tumour control and overall survival in patients with early stage Hodgkin lymphoma (4). There is also a new review from the recently established Cochrane Occupational Safety and Health Group examining the evidence on a variety of interventions to help cancer patients return to work (5).
Some of the reviews highlight the lack of robust evidence to support certain practices. For example, a new review finds no firm, published evidence to support the widely held opinion that eating a low-fat diet lowers cholesterol (6), another concludes that high-quality, large-scale randomised trials are needed if the routine use of edaravone is to be recommended for patients with acute intracerebral haemorrhage (7) and a substantively updated review finds that despite growing to 22 studies its conclusions are that there is not enough evidence to provide a reliable assessment of the efficacy of herbal treatment for rheumatoid arthritis (8).
The new issue of CDSR is accompanied by a collection of podcasts (http://www.cochrane.org/podcasts) and the Cochrane Journal Club continues to grow with recent topics including probiotics for acute infectious diarrhoea (9) and vitamin D to improve bone mineral density in children (10). The Journal Club resources include a specially prepared introductory summary, slideshow, author profile, collection of discussion points and related articles. They are available free at http://www.CochraneJournalClub.com.
In the following articles, two Cochrane authors who prepared podcasts for earlier issues of The Cochrane Library tell us in their own words about their reviews of strategies to expand health insurance coverage in children (11) and quinine to prevent muscle cramps (12).