Abstract 18048: Early Termination of Cardiovascular Clinical Trials Registered in ClinicalTrials.gov: Where Do We Stand?

Importance: Early termination of clinical trials represents a challenge in clinical research, yet little is known about the frequency and reasons for it. Objective: We aimed to describe reasons for termination, and identify the major predictors of early termination due to low recruitment.Study Selection: We reviewed all cardiovascular clinical trials registered in ClinicalTrials.gov from February 29, 2000 to January 17, 2013 and assessed information about trials that were completed and those that were terminated early.Data Extraction and Synthesis: The dataset was downloaded in XML containing all cardiovascular studies registered. The dataset was exported into R software to extract the values. Logistic regression models were developed to identify independent predictors of early termination due to low recruitment.Main Outcome Measure: Studies classified as completed or terminated prematurely, and reasons for termination. Results: Overall,684 of 6279 trials included (10.9%) were terminated prematurely. The main reason for early termination was lower than expected recruitment rates (278 trials; 53.6%); 24.1% of trials had no clear justification for premature termination. When comparing trials that terminated early due to low recruitment with those that were completed, we found that studies funded by the National Institutes of Health/ United States federal agencies (odds ratio [OR] 0.35, 95% confidence interval [CI] 0.14-0.89), studies of behavior/diet intervention (OR 0.35, 95% CI 0.19-0.65), and single-arm design studies (OR 0.57, 95% CI 0.42-0.78) were associated with a lower risk of early termination. University/hospital (OR 1.52, 95% CI 1.10-2.10) and mixed-source funded studies (OR 2.14, 95% CI 1.52-3.01) were associated with a higher likelihood of early termination due to lower than expected recruitment rates. Conclusions and Relevance: Early termination of interventional cardiovascular trials is common and most frequently due to low recruitment. Funding source, type of intervention, and study design were factors associated with early termination due to low recruitment and might be good targets for the improvement of clinical trial conduct.