Evaluating the generalizability of a large streamlined cardiovascular trial: comparing hospitals and patients in the dual antiplatelet therapy study versus the National Cardiovascular Data Registry.

BACKGROUND The Dual Antiplatelet Therapy Study is large streamlined clinical trial designed to evaluate antiplatelet treatment strategies in a broadly inclusive population of subjects treated with coronary stents. Whether large streamlined trials can successfully include a representative group of study sites and patients has not been formally assessed. METHODS AND RESULTS Within the National Cardiovascular Data Registry CathPCI Registry, we compared characteristics and outcomes of hospitals participating versus not participating in the Dual Antiplatelet Therapy Study. We also compared clinical and procedural characteristics of trial subjects undergoing percutaneous coronary intervention (PCI) with drug-eluting stents to contemporaneous patients within the National Cardiovascular Data Registry CathPCI Registry. Standardized differences between groups were estimated. Between September 2009 and July 2011, 1.1 million PCIs were performed among 1276 hospitals, of which 309 (24.2%) participated in the Dual Antiplatelet Therapy Study. Participating hospitals were larger (468 versus 311 beds), more frequently located in urban settings (61.2% versus 42.6%), and had higher annual PCI volumes (858 versus 378) compared with nonparticipating hospitals, although hospital case mix and procedural outcomes were similar. Compared with CathPCI patients, trial patients undergoing PCI with drug-eluting stents were similar with respect to race, sex, and rates of diabetes mellitus, hypertension, and smoking, although they had lower rates of prior cardiovascular disease. CONCLUSIONS Within the Dual Antiplatelet Therapy Study, clinical trial sites had similar patient case mix and clinical outcomes as nonparticipating sites. Although trial participants were representative of PCI patients with respect to race, sex and most comorbidities, they had a lower prevalence of chronic cardiovascular disease compared with registry patients. Although a streamlined cardiovascular clinical trial may successfully involve a large number of hospitals and rapidly enroll a diverse population of patients, differences between eligible patients and those actually enrolled remained. CLINICAL TRIAL REGISTRATION URL http://www.clinicaltrials.gov. Unique identifier: NCT00977938.