Regional differences in process of care and outcomes for older acute myocardial infarction patients in the United States and Ontario, Canada

Background — Previous comparisons of acute myocardial infarction (AMI) treatment between the United States and Canada are limited because they compared selected patients from randomized trials, used administrative data that lacked clinical detail, or did not consider regional differences in AMI treatment.

Methods and Results — We compared medication use, invasive cardiac procedure use, and 30-day risk-standardized mortality rates of 38 886 fee-for-service Medicare beneficiaries hospitalized with AMI in the United States and 5634 similarly aged patients in Ontario, Canada, from 1998 and 2001. Baseline characteristics and illness severity across the US regions and Ontario were not substantially different. Cardiac catheterization use in AMI patients was significantly higher in the United States compared with Ontario (38.7% versus 16.8%, P<0.001), but significant regional variations existed, in which the northeastern United States had significantly lower utilization rates (25.6%) compared with other US regions. β-Blocker use among ideal candidates was highest in the northeastern United States (77.6% versus 69.7% in the United States as a whole, P<0.001) and angiotensin-converting enzyme inhibitor use was highest in Ontario (69.1% versus 58.2% in the United States, P<0.001). Risk-standardized mortality rates at 30 days were not substantially different across the regions.

Conclusions — Previous studies have suggested a clear divergence in invasive cardiac therapy for AMI patients between the United States and Canada on the basis of healthcare financing and structural differences. Our findings of similar treatment patterns in the northeastern United States and Ontario suggest that regional practices may have a greater impact on treatment patterns than the respective healthcare delivery systems.