Coronary artery bypass graft surgery in Ontario and New York State: Which rate is right?

Background: Previous studies have shown that the rate of coronary artery bypass graft (CABG) surgery is much higher in New York State than in Ontario. Objective: To compare the service context and clinical characteristics of patients having CABG surgery in New York and Ontario. Design: Retrospective analysis of data from cardiac: surgery registries in New York and Ontario. Patients: All 16 690 patients in New York and 5517 patients in Ontario who had isolated CABG surgery in 1993. Measurements: Clinical characteristics of patients having CABG surgery and rates of CABG surgery by coronary anatomy. Results: The overall age-adjusted rate of isolated CABG surgery was 1.79 times (95% CI, 1.74 to 1.85) greater in New York than in Ontario. Patients who had CABG surgery in New York were more likely to be elderly and female and to have recently had myocardial infarction (P < 0.001), whereas patients who had CABG surgery in Ontario were more likely to have had left ventricular dysfunction and severe coronary artery disease (two-vessel disease with proximal left anterior descending disease, three-vessel disease, or left main disease) (P < 0.001). The relative rate of CABG surgery for left main disease was 2.53 times (Ci, 2.35 to 2.73) greater in New York than in Ontario but was 8.97 times (CI, 8.01 to 10.06) greater for patients with limited coronary artery disease (one-vessel or two-vessel disease without proximal left anterior descending disease). Conclusions: The higher rates of CABG surgery in New York are associated with higher rates of CABG surgery among the elderly, women, and patients who recently had myocardial infarction. Potential underservicing in Ontario is suggested by a lower rate of CABG surgery for left main disease; however, the higher rate of CABG surgery in New York is also associated with a strikingly higher rate of surgery in patients with limited coronary disease. Such trade-offs highlight the difficulty of defining an optimal rate of CABG surgery.