Reporting quality of randomized and non-randomized controlled trial abstracts from chicken research

In publication of a controlled trial article from health science research, the abstract is an important part that readers usually read first and then decide whether to read the whole article; therefore, information provided in the abstract should be adequate. The CONSORT (consolidated standards of reporting trials) for Abstracts checklist has been developed and used as a guideline for authors to prepare their manuscripts. This checklist has also been used as a tool to evaluate published abstracts. The objectives of this study were to evaluate reporting quality of randomized controlled trial (RCT) and non-RCT abstracts from chicken research and to determine factors associated with the reporting quality. We searched PubMed for RCT and non-RCT abstracts involving chicken research published between 2006 and 2015. The included abstracts were evaluated using the modified CONSORT for Abstracts checklist. The primary outcome was a mean overall quality score (OQS), which, for each abstract, was a sum of items reported in the modified CONSORT for Abstracts checklist. In addition, some pre-specified factors were evaluated for their association with the reporting quality using simple and multiple linear regression analyses. A total of 949 abstracts (n=262 for RCT and n=687 for non-RCT abstracts) were included and evaluated. Although OQS was significantly greater in RCT than in non-RCT abstracts (mean ± SD, 6.7 ± 0.9 vs 3.3 ± 1.1; P -value<0.001), both mean scores were still less than half of the full score of 15. Only 2 items—objective and conclusions—were adequately reported (>80%) in both types of the abstracts. Items concerning trial design, participants, interventions, randomization, and number randomized were adequately reported only in the RCT abstracts. In contrast, items concerning the study as randomized in the title, clearly defined primary outcome, blinding, numbers analyzed, estimated effect size and its precision for the primary outcome, trial registration, and funding were not reported or reported less than 5% in both RCT and non-RCT abstracts. In this study, 4 factors—year of publication, number of trials reported, number of experimental groups reported, and sample size reported—were associated with OQS. That is, abstracts with higher OQS were published more recently, reported a single trial rather than multiple trials, reported number of experimental groups rather than not reported, and reported sample size rather than not reported. These factors explained about 37.5% of the variance of OQS. In conclusion, reporting quality of RCT and non-RCT abstracts from chicken research was suboptimal. Therefore, efforts especially the development of specific guidelines based on the CONSORT for Abstracts checklist should be made for reporting controlled trial abstracts from chicken research to improve the transparency, completeness, and sufficiently detailed of reporting.