International participation in cardiovascular randomized controlled trials sponsored by the National Heart, Lung, and Blood Institute

Objectives: The aim of this study was to describe international enrollment and participation in National Institutes of Health (NIH)-sponsored cardiovascular randomized controlled trials (RCTs).

Background: RCTs provide the evidence base for major societal guidelines and profoundly influence patient care in the United States. Increased international involvement in clinical trials has been observed, but the rate of international enrollment in NIH-sponsored cardiovascular RCTs has not been described.

Methods: The NIH registry of clinical trials was searched for phase III or IV cardiovascular RCTs funded by the National Heart, Lung, and Blood Institute. Studies with outcomes of myocardial infarction, stroke, or death published between 1997 and 2009 were included. Rates of international enrollment were obtained from published data or personal communication with corresponding authors.

Results: Twenty-four studies met all inclusion criteria. Nineteen trials including 151,682 patients had international participation (IP), with median IP of 9.5% (range 0% to 100%). Coronary artery disease trials (11 studies) had nearly 50% international enrollment. High-risk trials and trials testing acute interventions tended to have higher rates of IP.

Conclusions: Cardiovascular RCTs sponsored by the National Heart, Lung, and Blood Institute have substantial rates of international enrollment, particularly coronary artery disease trials. Given questions of applicability and ethical and financial considerations, IP in U.S. clinical trials deserves further scrutiny.