CONSORT for Abstracts strongly recommends the use of structured abstracts for reporting RCTs [75
]; the full CONSORT Statement also supports their use [22
]. Since 1987 when the Ad Hoc Working Group for Critical Appraisal of the Medical Literature [25
] first published recommendations for the adoption of structured abstracts, many journals have promoted their use, and many different formats for structured abstracts now exist. We recognise that journals may have developed their own set of headings for abstracts [76
]. It is not the intention of this reporting guide to suggest changes to these headings but to recommend what information should be reported within them when describing a RCT.
It is important to note that, because of the space limitations of an abstract, it will only ever be possible to provide limited information about a trial report. CONSORT for Abstracts sets out to recommend what information should be reported within these constraints when describing a RCT. Readers of abstracts should always try to obtain more information about a trial and its results, either by accessing the full publication or, in the case of unpublished conference abstracts [1
], by contacting the authors for more information.
With the aim of greatly improving access to information about clinical trials and their results, the World Health Organization (WHO) recently established an International Clinical Trials Registry Platform. Their goal is to produce a single minimum standard for information that trialists should disclose before the trial begins [78
]. Moreover, as registration of the trial methods has become more common, several forces have begun to advocate for the disclosure of trial results in specially designed repositories linked to trial registers. In June 2007, endorsing the WHO's International Clinical Trials Registry Platform, the ICMJE published an editorial recommending a standard abstract format for reporting results. The ICMJE suggested that CONSORT for Abstracts may be one such option [80
]. At present, there is no formal consensus on international norms and standards for results reporting. The WHO International Clinical Trials Registry Platform has therefore established a Study Group on the Reporting of Findings of Clinical Trials to advise the WHO Registry Platform on matters related to the reporting of the findings of clinical trials. Full transparency and accountability require that all results of all trials are made available to the public in a timely manner.
Like the CONSORT Statement, CONSORT for Abstracts has been developed primarily for reporting the main results of parallel group RCTs (i.e., those relating to the prespecified primary outcome). There may well be instances where different types of trial information, such as composite outcomes, or different designs, such as cluster trials or noninferiority and equivalence trials, will require additional information not covered in this explanation and elaboration document. Possible additional abstract extensions may be warranted, as has been done for the CONSORT Statement for full reports [35
The length of an abstract reporting a RCT using the CONSORT for Abstracts checklist is difficult to estimate. In developing the checklist 250 to 300 words were found to be sufficient to address all of the items in the checklist. Worked examples of using the CONSORT for Abstracts checklist are available on the CONSORT website at http://www.consort-statement.org/
. In the past, MEDLINE has truncated journal abstracts at 250 words [82
]. This has resulted in many journals setting word limits for abstracts in their journals at 250 words. However, since 2000 the National Library of Medicine increased the word limit for an abstract appearing in MEDLINE to 10,000 characters, which equates to over 1,000 words. While most abstract reports will not require anywhere near 1,000 words, such a word length will be sufficient to report even the most complex of trials in abstract form [82
Clear, transparent, and accurate reporting of research is important because it enables readers to understand what was done and hence to evaluate the reliability and relevance of the findings. This extension of the CONSORT Statement aims to improve the reporting of RCTs in both the abstracts of journal articles and conference proceedings [83
]. When using the CONSORT for Abstracts checklist we encourage authors to use it in conjunction with this explanation and elaboration document. We encourage journals and conference organisers to endorse the use of CONSORT for Abstracts by modifying their “Instructions to Authors” and drawing their readers' attention to this reporting guidance, perhaps through an editorial or by including a link to the checklist on the conference website. The most important benefit will be to enable readers to use abstracts more effectively and to assess the validity of the research more precisely. When key aspects of study methods are omitted, reader assessments are less certain, and might well take longer to make.