Background: By definition, an abstract is a brief summary of a review of a particular subject and is often used to help the reader quickly ascertain the paper's purpose. Currently, there are 16 attributes (both essential or desirable) recommended by Methodological Expectations of Cochrane Intervention Reviews (MECIR) standards that need to be met while writing an abstract. Our own review included 132 trials, 4.6 million participants, > 40 outcome measures; and its abstract initially had 2264 words. We were forced to make a ‘trade-off’ between meeting those standards and fitting within the limit of 1000 words.

Objectives: This article is aimed at measuring the length of abstracts of recent Cochrane Systematic Reviews (CSRs).

Methods: Systematic literature searches of MEDLINE (via Pubmed in March 2016) were undertaken using the search terms: systematic review and Cochrane Database of Systematic Reviews. A random sample of 50 recent CSRs was chosen using a random number generator. Descriptive statistics have been undertaken to calculate range, means and standards deviations of the published reviews.

Results: All the CSRs were published in 2016. The average length of abstract was 603.1 words (standard deviation = 156; median = 604; range: 305-969).

Conclusions: With the reviews sometimes exceeding 100 primary trials, it is often difficult to ascertain the right balance, i.e. succinct and comprehensive at the same time. Abstracts of less than 500 words can be a useful alternative to often unnecessarily lengthy summaries. By shortening abstracts, authors of CSRs must make a review finding usable to policymakers, researchers, clinicians or other stakeholders.