Effect of Persistence with Drug Therapy On the Risk of Myocardial Re-infarction.

OBJECTIVE We conducted a study to assess the effect of persistence with therapy in the use of statins, beta blockers, or calcium-channel blockers on the recurrence of myocardial infarction or death in a Medicaid high-risk, largely female, African-American population. STUDY DESIGN This was a prospective nonconcurrent cohort, longitudinal data analysis of medical and pharmacy claims of acute myocardial infarction (AMI) patients from Medicaid managed care organizations between January 1, 2002, and December 31, 2004. METHODS Cox proportional hazards models were used to predict the likelihood of a re-infarction as a function of persistence with the use of the initial medication after an AMI. We made adjustments for age, race, sex, heart disease, and other comorbidities as well as the pharmacotherapies prescribed. RESULTS Among 515 AMI patients (58.1% female, 46% African-American), the most prevalent comorbidities were hypertension (90.9%) and heart disease (80.6%). Most initial AMIs were non-transmural. Discontinuation of statins, beta blockers, or calcium-channel blockers after an AMI increased the likelihood of a re-infarction (hazard ratio, 1.66; 95% confidence interval, 1.03-2.69). Concurrent heart disease, hyperlipidemia, or renal disease significantly increased the probability of having a re-infarction, but age, race, and sex did not significantly predict the likelihood of re-infarction or death. CONCLUSION Persistence of therapy in the use of the initial AMI-preventive medication after an AMI was effective in avoiding re-infarction or death. Heart disease, renal disease, and hyperlipidemia increased the likelihood of an adverse outcome.