Eligibility criteria in systematic reviews published in prominent medical journals: a methodological review

Rationale and aim Clear and logical eligibility criteria are fundamental to the design and conduct of a systematic review. This methodological review examined the quality of reporting and application of eligibility criteria in systematic reviews published in three leading medical journals. Methods All systematic reviews in the BMJ, JAMA and The Lancet in the years 2013 and 2014 were extracted. These were assessed using a refined version of a checklist previously designed by the authors. Results A total of 113 papers were eligible, of which 65 were in BMJ, 17 in The Lancet and 31 in JAMA. Although a generally high level of reporting was found, eligibility criteria were often problematic. In 67% of papers, eligibility was specified after the search sources or terms. Unjustified time restrictions were used in 21% of reviews, and unpublished or unspecified data in 27%. Inconsistency between journals was apparent in the requirements for systematic reviews. Conclusions The quality of reviews in these leading medical journals was high; however, there were issues that reduce the clarity and replicability of the review process. As well as providing a useful checklist, this methodological review informs the continued development of standards for systematic reviews.