There are differences between eligible, real-world patients and patients enrolled in the DAPT Study, including a lower prevalence of chronic cardiovascular disease, according to a study published Nov. 16 in Circulation: Cardiovascular Quality Outcomes.

The study was led by Robert W. Yeh, MD, MSc, FACC, Cardiology Division, Department of Medicine, Massachusetts General Hospital, and compared characteristics and outcomes of DAPT Study-participating and nonparticipating hospitals within the ACC’s Cath PCI Registry. Yeh and his team also compared the clinical and procedural characteristics of trial subjects undergoing percutaneous coronary intervention (PCI) with drug-eluting stents to patients within the CathPCI Registry.

Results showed that between September 2009 and July 2011, 1.1 million PCIs were performed among 1,276 hospitals, of which 309 (24.2 percent) participated in the DAPT Study. Participating hospitals were larger (468 vs. 311 beds), more frequently located in urban settings (61.2 percent vs. 42.6 percent), and had higher annual PCI volumes (858 vs. 378) compared with nonparticipating hospitals. However, hospital case mix and procedural outcomes were similar. Compared with CathPCI patients, trial patients undergoing PCI with drug-eluting stents had similar race, sex, and rates of diabetes mellitus, hypertension, and smoking, but had lower rates of prior cardiovascular disease.

The authors conclude that their study demonstrated that “a large streamlined clinical trial can be conducted in a manner that involves a large number of hospitals, enrolls rapidly, and includes a diverse population of patients while also preserving key design features to minimize bias: randomization and central adjudication. Although sites participating in such a trial had similar adjusted clinical outcomes, they still differ from nonparticipating sites in many ways, a factor which should be considered when generalizing results to clinical practice. In addition, patient enrolled in the DAPT Study were, on average, a lower risk population compared with potentially eligible patients, despite limited exclusion criteria. These findings have important implications for the evaluation and interpretation of large inclusive randomized trials.”

The authors add that they believe their study “further highlights the potential uses of registry data to inform clinical trial external validity and address a key critique of randomized clinical trials.”

Keywords: Drug-Eluting Stents, Diagnosis-Related Groups, Massachusetts, Hypertension, Diabetes Mellitus, Smoking, Hospitals, General, Percutaneous Coronary Intervention, National Cardiovascular Data Registries

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