A descriptive analysis of the characteristics and the peer review process of systematic review protocols published in an open peer review journal from 2012 to 2017

BACKGROUND: An a priori design is essential to reduce the risk of bias in systematic reviews (SRs). To this end, authors can register their SR with PROSPERO, and/or publish a SR protocol in an academic journal. The latter has the advantage that the manuscript for the SR protocol is usually peer-reviewed. However, since authors ought not to begin/continue the SR before their protocol has been accepted for publication, it is crucial that SR protocols are processed in a timely manner. Our main aim was to descriptively analyse the peer review process of SR protocols published in ‘BMC Systematic Reviews’ from 2012 to 2017. METHODS: We systematically searched MEDLINE via PubMed for all SR protocols published in ‘BMC Systematic Reviews’ between 2012 and 2017, except for protocols for overviews, scoping reviews or realist reviews. Data were extracted from the SR protocols and Open Peer Review reports. For each round of peer review, two researchers judged the extent of revision (minor/major) based on the reviewer reports. Their content was further investigated by two researchers in a random 10%-sample using PRISMA-P as a guideline. All data were analysed descriptively. RESULTS: We identified 544 eligible protocols published in ‘BMC Systematic Reviews’ between 2012 and 2017. Of those, 485 (89.2%) also registered the SR in PROSPERO, the majority (87.4%) before first submission of the manuscript for the SR protocol (median 49 days). The absolute number of published SR protocols increased from 2012 to 2017 (21 vs 145 protocols), as did the median processing time (61 vs 142 days from submission to acceptance) and the proportion of protocols requiring a major revision after first peer review (19.1% vs 52.4%). Reviewer comments most frequently addressed the PRISMA-P item ‘Eligibility criteria’. Overall, 76.0% of the reviewer comments suggested more transparency. CONCLUSIONS: The number of published SR protocols increased over the years, but so did the processing time. In 2017, it took several months from submission to acceptance, which is critical from an author’s perspective. New models of peer review such as post publication peer review for SR protocols should be investigated. This could probably be realized with PROSPERO. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12874-019-0698-8) contains supplementary material, which is available to authorized users.