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Table 5 A 12-heading HS format recommended for the reporting of RCT abstracts, modified from the original Haynes proposal for structured abstracts [9] and the CONSORT for Abstracts guidelines [23]

From: Structure formats of randomised controlled trial abstracts: a cross-sectional analysis of their current usage and association with methodology reporting

Heading Content instruction
1. Objective State the specific objective or question addressed in the trial. If more than one objective is addressed, indicate the primary objective (based on the predetermined primary outcome) and key secondary objectives.
2. Designa Use the term ‘randomised’ to indicate that this is an RCT; describe explicitly the design of the trial (e.g. parallel group, cluster randomised, crossover, factorial, superiority, equivalence or noninferiority, or a combination of these designs); report the duration of follow-up.
3. Settinga Provide information about the trial setting, including the level of care (e.g. primary, secondary, tertiary care) and number of participating centres; describe the geographical location if important (e.g. population research in communities).
4. Participants and interventionsb Provide eligibility criteria for participants (e.g. demographics, clinical diagnosis, comorbid conditions) and details about the interventions for each group (e.g. dose, route and duration of administration, surgical procedure/technique, name of drug, manufacturer of inserted device, main content of education/lifestyle intervention activity); state the number of participants randomised to each group and the unit of randomisation;
5. Main outcome measure(s)c Clearly state what the primary outcome was (i.e. the predetermined outcome considered of greatest importance and usually the one used in sample size calculation) and when it was assessed; describe key secondary outcome if important, make sure that primary outcome and secondary outcomes are distinguished; if the trial abstract focuses on a secondary outcome, identify both this outcome and the primary outcome.
6. Sequence generationa Describe the methods used for random sequence generation (e.g. random number table, computer random number generator, coin tossing, minimisation).
7. Allocation concealmenta Describe the methods used for allocation concealment (e.g. central allocation, sequentially numbered identical containers, sequentially numbered opaque, sealed envelopes); state ‘None’ when no measures were taken to conceal allocation.
8. Blinding (masking) State the blinded parties among participants, caregivers/personnel, data assessors and data analysts (automatically indicating that those unmentioned parties were not blinded); avoid generic descriptions (e.g. single-blind, double-blind); state ‘None’ if blinding was not used or not possible/appropriate in the trial.
9. Results Describe the number of participants in each group that were included in the analysis; for the primary outcome, state a result for each group, the estimated effect size and its precision; report any important adverse events (if no adverse events occurred state this explicitly).
10. Conclusions Give a general interpretation that is consistent with the trial results, with benefits and harms balanced.
11. Trial registrationa Provide the registration number and name of trial register.
12. Fundinga Report the source of funding.
  1. HS Highly structured, CONSORT for Abstracts: the CONSORT (Consolidated Standards of Reporting Trials) extension guidelines for reporting of RCT abstracts [23]
  2. aFor brevity, content under these headings can be written in phrases rather than complete sentences
  3. bTwo Haynes headings 9 are combined together to facilitate the reporting of unit of randomisation and number of randomised participants, for example:
  4. (1) Sixty patients with breast cancer of stage 0 to III were randomly assigned in a 2:1 ratio to receive surgery technique A (A group) or surgery technique B (B group);
  5. (2) Four classes of healthy high school students were randomly allocated to two additional 40-min courses of outdoor activities (intervention group, 2 classes, 60 students) or their usual pattern of activity (control group, 2 classes, 52 students)
  6. cUsing multiple primary outcomes in a trial incurs interpretation problems and is not recommended [59]