Aims: Pre-registration of study protocols in accessible databases is required for publication of study results in high-impact medical journals. Nonetheless, data on characteristics of clinical trials registered in these databases and their outcome, in terms of result reporting and publication are limited.
Methods and results: We searched for interventional, late-phase cardiovascular disease (CVD) studies in adults registered in Clinicaltrials.gov. first posted after 1 January 2013 and completed up to 31 December 2018. Data on study design, result reporting, and publication were collected, and potential associations with a pre-defined set of explanatory factors were examined. In total, 250 CVD trials were included in the analysis. Of these, 193 (77.2%) were randomized studies, 99 (39.6%) open label designs, and 126 (50.4%) had industry as main sponsor. One hundred and seventy-nine trials (71.6%) evaluated the effect of drugs and 27 (10.8%) evaluated devices. The most common primary outcomes were non-clinical endpoints (76.0%), with only 17% of studies evaluating clinical endpoints. Industry-funded trials focused on patent-protected drugs and devices more often than non-industry-funded trials (72.0% vs. 30.6%, P < 0.001 and 55.0% vs. 26.3%, P = 0.033, respectively). Sixty-three studies (25.2%) had results posted on clinicaltrials.gov, and 116 (46.4%) had results published in the scientific literature. In multivariate analysis, industry sponsorship was statistically significantly associated with results posting [odds ratio (OR): 3.38; 95% confidence interval (CI): 1.56-7.30, P = 0.002] and publication (OR: 0.41; 95% CI: 0.23-0.75, P = 0.004).
Conclusion: Among late-stage cardiovascular trials only one-fourth had results posted on clinicaltrials.gov and <50% had results published. Industry sponsors were more likely to invest in research on patent-protected drugs and devices than were non-industry sponsors. Industry-sponsored studies were more likely to have their results posted, but less likely to have their results published in the scientific literature.
Keywords: Research ethics; Research methodology; Study reporting.
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