Rigor, reproducibility, and transparency of randomized controlled trials in obstetrics and gynecology

Background: Randomized controlled trials are considered the highest level of evidence but fewer than half are reproducible. A rigorous methodology improves trial quality, but reproducibility may be limited by a lack of transparency in reporting. The Consolidated Standards of Reporting Trials guidelines define reporting standards, and pretrial registration requires a predefined methodology and predefined outcomes.

Objective: We evaluated obstetrics and gynecology trials published in 6 journals in terms of their adherence to the Consolidated Standards of Reporting Trials guidelines. Second, we evaluated pretrial registration compliance and concordance between the registry and publication. Furthermore, we evaluated the differences in trial characteristics among randomized controlled trials with the highest level of compliance and those with lower levels of compliance and adherence to guidelines by journal type.

Study design: This was a cross-sectional study of obstetrics and gynecology trials published between 2017 and 2019 in 6 journals (American Journal of Obstetrics & Gynecology, BJOG: An International Journal of Obstetrics and Gynaecology, Obstetrics & Gynecology, The Journal of the American Medical Association, The Lancet, and The New England Journal of Medicine). Randomized controlled trials were identified via PubMed and manual journal archive searches. The primary outcome was adequate compliance with the Consolidated Standards of Reporting Trials guidelines defined as ≥80% of the checklist items present. Secondary outcomes included completion of pretrial registration and concordance between the pretrial registration and publication in terms of the outcomes and sample size. We compared the characteristics between trials with adequate compliance and those with inadequate compliance. Secondary analyses included comparisons of characteristics of the trials in the top quartile for compliance with the Consolidated Standards of Reporting Trials guidelines with those of the trials in lower quartiles and compliance with guidelines in obstetrics-gynecology vs non-obstetrics-gynecology journals. In an exploratory analysis, trends in compliance with the Consolidated Standards of Reporting Trials guidelines across the study period were assessed. A post hoc sensitivity analysis evaluated the outcomes after the exclusion of 2 retracted trials.

Results: Of the 170 trials included, 80% (95% confidence interval, 74%-86%) were adequately compliant with the Consolidated Standards of Reporting Trials manuscript guidelines and 66% (95% confidence interval, 59%-73%) were compliant with the abstract guidelines. Nearly all trials (98%) reported pretrial registration. Concordance between pretrial registration and publication in terms of the primary outcomes was identified for 77% of the trials, concordance in terms of the secondary outcomes was observed in 32% of the trials, and concordance in terms of sample size was observed in 60% of the trials. Trials with adequate compliance were more likely to be preregistered, include an a priori power calculation, and use an intent to treat analysis. Trials in the top quartile for compliance with the Consolidated Standards of Reporting Trials guidelines were more likely to be multicenter, international, and government funded. More trials from non-obstetrics-gynecology journals were in the top quartile for compliance with the Consolidated Standards of Reporting Trials guidelines than trials from obstetrics-gynecology journals (64.9% vs 25.7%; P<.001). No significant trends in adequate compliance were identified across the study period. Results did not differ significantly in the sensitivity analysis.

Conclusion: Of all the trials included, 20% of obstetrics-gynecology trials published in 6 high-impact journals were not compliant with the Consolidated Standards of Reporting Trials guidelines, and there were major discrepancies between pretrial registration and publication. Transparency, reproducibility, and scientific rigor in obstetrics and gynecology trial reporting needs to be improved.