Regional variation in the management of acute myocardial infarction in the province of Quebec.

BACKGROUND: Previous studies have shown that there are differences in acute myocardial infarction (AMI) management in Canada and in the United States. However, there has been little research to evaluate regional variations in AMI treatment and outcomes for Canadian patients.

OBJECTIVE: To determine whether regional variation in the management of AMI in Quebec has an impact on patient mortality and morbidity.

PATIENTS AND METHODS: Discharge summary and physician claims databases for 76,012 patients with AMI were used between January 1, 1988 and December 31, 1995 to build 16 cohorts for the administrative regions of the province of Quebec. The clinical characteristics, prescription medications, cardiac procedure use, readmissions for cardiac complications and mortality across the different regions were compared.

RESULTS: After adjusting for age and sex, discharge prescriptions resulted in the following ranges: angiotensin-converting enzyme inhibitors 34% to 46% of patients, acetylsalicylic acid 49% to 77%, beta-blockers 32% to 54%, calcium channel blockers 25% to 48%, lipid-lowering drugs 4% to 16% and nitrates 76% to 86%. Procedure use varied considerably across the province during the initial 10 days post-AMI (catheterization 3% to 28%; percutaneous coronary intervention 1% to 8%, and coronary artery bypass surgery 0 to 2%), as well as one year after discharge (27% to 47%, 8% to 17%, and 6% to 12%, respectively). Some variation was observed for cardiac complications after one year (unstable angina 9% to 21%; congestive heart failure and recurrent myocardial infarction, no major variation). However, there was no significant regional variation observed for one-year and three-year mortality rates (19% to 22% and 27% to 31%, respectively).

CONCLUSIONS: There was marked regional variation in the rates of discharge prescriptions for cardiac medications and cardiac procedures in patients who have had an AMI in Quebec. These results suggest that the type of treatment received for an AMI depends on the region in which the patient lives. This variation appeared to affect readmission rates for unstable angina, but had no impact on mortality or other cardiac complications post-AMI.