Cochrane review abstracts are getting longer, but this has no large impact on the reporting quality.

Objective: To evaluate the reporting of abstracts of Cochrane Reviews according to PRISMA-A and to investigate a possible association with the abstract´s length.
Methods: This is a retrospective, observational study based on all Cochrane Reviews indexed in Medline (via PubMed) until November 18, 2022. In the second part, a random sample of 440 abstracts was drawn, in which PRISMA-A adherence was assessed by two independent reviewers. Analyses were stratified by the year of publication and the number of words.
Results: Overall, the median number of words of the 15,188 included abstracts was 469 (IQR 389-686 words), steadily increasing from 353 words in 2000 to 838 words in 2022, with less than one percent of the abstracts in 2022 having ≤ 300 words (in 2000: 30.7%). Analyses on PRISMA-A adherence in the random sample showed a mean score of 6.1 out of 12 fully reported items. Stratified by year, PRISMA-A adherence increased, with higher word counts in 2000-2010 and 2011-2015, while there was no difference in PRISMA-A adherence by abstract length in 2016-2022.
Conclusion: Over the years, abstracts of Cochrane Reviews have become longer, running up to 1000 words. This conflicts with the Cochrane Handbook, which recommends a maximum length of 400 until it was aligned with MECIR in 2019, which has recommended a length of <700 words since 2012 but allows up to 1000 words. It is debatable whether such long abstracts meet the key goals of abstracts of being informative, accurate, appealing, and concise.
(© 2023 The Authors. Journal of Evidence-Based Medicine published by Chinese Cochrane Center, West China Hospital of Sichuan University and John Wiley & Sons Australia, Ltd.)