Title and structured abstract

Item 1b: Structured summary of the trial design, methods, results, and conclusions

Explanation

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Transparent and sufficiently detailed abstracts are important because readers often base their assessment of a trial on such information. Some readers use an abstract as a screening tool to decide whether to read the full article. However, not all trials are freely available and some health professionals and other users do not have access to the full trial reports [27].

A journal abstract should contain sufficient information about a trial to serve as an accurate record of its conduct and findings, providing optimal information about the trial within the space constraints and format of a journal. A properly constructed and written abstract helps individuals to assess quickly the relevance of the findings and aids the retrieval of relevant reports from electronic databases [28]. The abstract should accurately reflect what is included in the full journal article and should not include information that does not appear in the body of the paper. In addition, abstracts should not be a distorted representation of the trial results. Studies comparing information reported in a journal abstract with that reported in the text of the full publication have found claims that are inconsistent with, or missing from, the body of the full article [29-32]. Abstracts are also frequently reported with spin defined as a distorted representation of the study results [33-35]. Authors should avoid selectively reporting only statistically significant secondary outcomes or subgroup analyses. Conversely, omitting important harms from the abstract could seriously mislead interpretation of the trial findings and benefit-to-harms balance that is critical for decision making [36 37].

An extension to CONSORT 2001 provided a list of essential items that authors should include in a journal (or conference) abstract when reporting the main results of a randomised trial [38]. A systematic review of 10 meta-research studies examined the reporting quality of abstracts of randomised trials and found improvements in reporting following publication of this extension [39]. Table 2 provides a list of essential items to include in an abstract; it is based on the CONSORT for Abstracts extension [40] and has been updated to reflect changes made to the main CONSORT checklist. We strongly recommend the use of structured abstracts for reporting randomised trials. They provide readers with information about the trial under a series of headings pertaining to the design, conduct, analysis and interpretation [41]. Some studies have found that structured abstracts offer greater value and information coverage than the more traditional descriptive abstracts [42 43] and allow readers to find information more easily [44]. We recognise that journals have their own structure for reporting abstracts. It is not our intention to suggest changes to these formats, but to recommend what information should be reported.