Table 1

The 10 most important and poorly reported consort items as defined by a group of experts on the CONSORT statement.30for better understanding key features were summarised within a short explanation (extracted from the CONSORT explanation and elaboration paper11 as well as from the COBWEB tool)33

ItemSectionCONSORT itemShort explanation
1Outcomes (6a)Completely defined pre-specified primary outcome measure, including how and when it was assessedIs it clear (i) what the primary outcome is (usually the one used in the sample size calculation), (ii) how it was measured (if relevant; eg, which score used), (iii) at what time point and (iv) what the analysis metric was (eg, change from baseline, final value)?
2Sample size (7a)How sample size was determinedIs there a clear description of how the sample size was determined, including (i) the estimated outcomes in each group, (ii) the α (type I) error level, (iii) the statistical power (or the β (type II) error level) and (iv) for continuous outcomes, the SD of the measurements?
3Sequence generation (8a)Method used to generate random allocation sequenceDoes the description make it clear if the ‘assigned intervention is determined by a chance process and cannot be predicted’?
4Allocation concealment (9)Mechanism used to implement random allocation sequence (such as sequentially numbered containers), describing any steps taken to conceal the sequence until interventions were assignedIs it clear how the care provider enrolling participants was made ignorant of the next assignment in the sequence (different from blinding)? Possible methods can rely on centralised or ‘third-party’ assignment (ie, use of a central telephone randomisation system, automated assignment system, sealed containers).
5Blinding (11a)If done, who was blinded after assignment to interventions (eg, participants, care providers, those assessing outcomes)Is it clear if (i) healthcare providers, (ii) patients and (iii) outcome assessors are blinded to the intervention? General terms such as ‘double-blind’ without further specifications should be avoided.
6Outcomes and estimation (17a/b)For the primary outcome, results for each group, and the estimated effect size and its precision (such as 95% CI)Is the estimated effect size and its precision (such as SD or 95% CI) for each treatment arm reported? When the primary outcome is binary, both the relative effect (risk ratio, relative risk or OR) and the absolute effect (risk difference) should be reported with CI.
7Harms (19)All-important harms or unintended effects in each groupIs the number of affected persons in each group, the severity grade (if relevant) and the absolute risk (eg, frequency of incidence) reported? Are the number of serious, life threatening events and deaths reported? If no adverse event occurred this should be clearly stated.
8Registration (23)Registration number and name of trial registryIs the registry and the registration number reported? If the trial was not registered, it should be explained why.
9Protocol (24)Where trial protocol can be accessedIs it stated where the trial protocol can be assessed (eg, published, supplementary file, repository, directly from author, confidential and therefore not available)?
10Funding (25)Sources of funding and other support (such as supply of drugs) and role of fundersAre (i) the funding sources, and (ii) the role of the funder(s) described?
  • COBWEB, Consort-based WEB tool; CONSORT, CONsolidated Standards of Reporting Trials.