Abstract
OBJECTIVES: The aim of this study was to assess the influence of enrolling site location and enrollment performance on the generalizability of STICH (Surgical Treatment for Ischemic Heart Failure) trial results. BACKGROUND: The international STICH trial seeks to define the role of cardiac surgery for patients with ischemic cardiomyopathy. METHODS: Baseline characteristics of 2,136 randomized STICH patients were entered into a multivariate equation created using the Duke Databank for Cardiovascular Diseases to predict their 5-year risk for death without cardiac surgery. Patients ordered by increasing predicted risk were assigned to 1 of 32 risk at randomization (RAR) groups created to share one-thirty-second of total predicted deaths. Numbers of patients sharing the same RAR group were compared between higher and lower enrolling site groupings and for countries tending to enroll high- or low-risk patients. RESULTS: Country of enrollment was a stronger determinant of risk diversity than site enrollment performance among patients enrolled at 127 sites in 26 countries. Mean RAR differences among countries ranged from 9.4 (Singapore) to 18.6 (Germany). However, 1,614 of 2,136 patients (76%) from countries enrolling lower-risk patients shared the same RAR group with patients from countries enrolling higher-risk patients. Baseline characteristics responsible for risk differences of patients enrolled in the 2 country groupings were sufficiently similar to exert little influence on clinical decision making. CONCLUSIONS: STICH randomized patients are characterized by a continuous spectrum of risk, without discordant dominance from any site or country. Clinical site diversity promises to enhance the generalization of STICH trial results to a broad population of patients with ischemic cardiomyopathy. (Comparison of Surgical and Medical Treatment for Congestive Heart Failure and Coronary Artery Disease; NCT00023595).