1. According to the Cochrane Handbook, a “stable” review is “one that is highly likely to maintain its current relevance for the foreseeable future.” Reaching certainty: A descriptive study of “stable” Cochrane Reviews and coming to firm conclusions To monitor the extent and reasons for Cochrane reviews (CR) being designated stable, and to describe the reviews designated by the CR authors as having a conclusion that would be unlikely to change with new trials (called here a “firm conclusion”). BackgroundResults TABLE. Reviews declared “stable” with firm conclusions (New trials would be unlikely to change conclusions) Selegeline for Alzheimer's disease Short vs long antibiotics for acute otitis media Myobacterium immunotherapy for tuberculosis Thiamine for Alzheimer's disease Immediate vs deferred AZT for HIV D-cycloserine for Alzheimer's disease Condoms to reduce heterosexual HIV transmission DOT (directly observed therapy) for tuberculosis Male circumcision to prevent heterosexual HIV acquisition in men Nonoxynol-9 for preventing heterosexual HIV transmission to women Nonoxynol-9 for preventing heterosexual STI transmission to women H-pylori eradication vs non-eradication therapy to prevent gastric bleeding Oral vs IV rehydration for children with dehydration from gastroenteritis Calcium antagonists for Duchenne muscular dystrophy Electronic mosquito repellents to prevent mosquito bites and malaria infection Microwave therapy for cervical entropion FIGURE. Reasons given for declaring Cochrane reviews stable (n = 154) Hilda Bastian, National Center for Biotechnology Information, National Library of Medicine, NIH, USA Lars G. Hemkens, Basel Institute for Clinical Epidemiology and Biostatistics, University Hospital Basel, Basel, Switzerland Objectives Methods Conclusions We had previously identified six categories of Cochrane reviews designated “stable” by review groups (CRGs): 1. Little or no further evidence expected (“No data expected”) 2. Intervention discontinued or superseded (“Intervention discontinued”) 3. Update required, but in more than 2 years (“Longer update interval”) 4. Review has been or will be superseded by a new review (“Review superseded”) 5. Will search every 2 years, but only update if a new trial appears (“Monitor”) 6. New trials would be unlikely to change conclusions (“Firm conclusions”) Stable reviews were identified in the February 2013 Issue of the Cochrane Database of Systematic Reviews (CDSR). Data on the year and reasons of the designation “stable” were extracted from the “What’s new” section. When reasons were not clearly reported there, the abstract, discussion and conclusions sections were searched. Both authors agreed on categories. The conclusions and body of evidence of reviews with firm conclusions were described. The use of the “stable” category is determined on a case-by- case basis, with highly variable practice among CRGs. Reasons for the decision to designate a review “stable” are often poorly reported. Cochrane authors rarely both conclude that new trials would be unlikely to change the conclusions of their reviews and designate the review as “stable”. They may be more likely to do so when there is an absence of evidence of effect. Partially supported by the NIH intramural research program. There were 180 stable reviews among 5137 “non- withdrawn” intervention and diagnostic CRs in the CDSR (3.5%). The number of reviews being designated stable has been increasing in recent years. Reasons for the designation were often not explained in the “What’s new” section, and a total of 26 reviews gave no clear reason in the review for the categorizing reviews as stable (14%). Where a reason was given (154 reviews), the most common category was a belief that future trials were unlikely (36%) (see Figure). Only 16 reviews (Table) were designated as having firm conclusions, mostly because there was no evidence of benefit, or any benefits were either clinically unimportant or not sustained (11/16 reviews, 69%).