Drug prescriptions after acute myocardial infarction: dosage, compliance, and persistence

Although it has been well documented that aspirin, beta-blockers, angiotensin-converting enzyme (ACE) inhibitors, and lipid-lowering drugs are under-prescribed for patients with acute myocardial infarction (Am Heart J 2003;145:438-44.), few studies have examined dosage and long-term compliance and persistence patterns for the use of these drugs after AMI.

Using Quebec administrative data on all elderly (aged > or =65 years) survivors of hospital admissions for AMI between 1996 and 1998 (n = 14,057), we studied the discharge prescriptions, dosages, patient compliance, and persistence during this period for aspirin, beta-blockers, ACE inhibitors, and lipid-lowering drugs.

Rates of discharge medications were suboptimal (aspirin 65%, beta-blockers 54%, ACE inhibitors 45%, lipid-lowering drugs 21%). Most patients with prescriptions for aspirin and ACE inhibitors were prescribed dosages equivalent to those administered in clinical trials (99% and 88%, respectively). In contrast, only 20% of patients with beta-blocker prescriptions and 48% of patients with lipid-lowering drug prescriptions were prescribed clinical trial doses. For patients with discharge prescriptions, 1-year compliance rates were high (aspirin 74%, beta-blockers 74%, ACE inhibitors 70%, lipid-lowering drugs 84%), as were the 1-year persistence rates (aspirin 71%, beta-blockers 72%, ACE inhibitors 69%, lipid-lowering drugs 80%).

Although cardiac drugs are under-prescribed to patients with AMI, once prescribed, patients are likely to adhere to these prescriptions, with high rates of compliance and persistence.