Use of Secondary Prevention Drug Therapy in Patients With Acute Coronary Syndrome After Hospital Discharge

BACKGROUND: Acute coronary syndrome includes life-threatening clinical conditions ranging from unstable angina to non-Q-wave myocardial infarction and Q-wave myocardial infarction that are a major cause of emergency medical care and hospitalization in the United States. The American College of Cardiology/American Heart Association (ACC/AHA) guidelines on the management of patients with unstable angina and non-ST-segment elevation myocardial infarction (2002-2004) recommend (1) angiotensinconverting enzyme (ACE) inhibitors or angiotensin II receptor blockers (ARBs) for ACE inhibitor intolerance, (2) beta-blockers, and (3) statins for long-term treatment of patients after an acute coronary event. OBJECTIVES: To examine rates of use of 3 key evidence-based drug therapies (ACE inhibitors/ARBs, beta-blockers, and statins) after hospital discharge for patients with acute coronary syndromes (ACS). METHODS: The study cohort was identified using medical claims from commercial health plans within a managed care organization located in the Mid-Atlantic states, with approximately 3.4 million members with medical benefits of whom 1.2 million members (35.3%) had pharmacy benefits. Members were included if they were (1) aged e 18 years, (2) continuously enrolled with the same commercial plan from January 1, 2003, through December 31, 2005, (3) had any medical claims for hospitalization for ACS defined by International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes 410.xx (acute myocardial infarction) or 411.1 (intermediate coronary syndrome) during the sample identification period from July 1, 2003 through June 30, 2004, and (4) had no medical claims for ACS hospitalizations from January 1, 2003, through June 30, 2003, in any of 10 diagnosis fields on an inpatient hospital claim. Pharmacy claims for ACE inhibitors, ARBs, beta-blockers, and statins were obtained for 18 months following each index date, defined as the earliest ACS diagnosis date during the identification period. Utilization was defined as the member having at least 1 pharmacy claim within each class from index date to 3 months post-index date. Five time periods were examined to assess therapy: - 180 to 0 days (6 months prior), 0 to 90 days (3 months), 0 to 180 days (6 months), 0 to 365 days (12 months), and 0 to 548 days (18 months) following the index date. ACE inhibitors and ARBs were considered together (i.e., a patient had to have at least 1 pharmacy claim for an ACE inhibitor or an ARB). Logistic regression analyses were used to predict use of the 3 drug classes for patients with different clinical (diagnosis and prior use) and demographic (sex and age) characteristics. RESULTS: The study cohort included 1,135 patients (0.27% of 424,526 continuously enrolled members) with ACS as defined by ICD-9-CM codes in medical claims from July 1, 2003, to June 30, 2004. Nearly 65% of the sample patients were men (n = 734 men and n = 401 women), with a mean (standard deviation [SD]) age of 63.8 (SD 13.1) years. Of the 1,135 members with ACS, 588 (51.8%) had at least 1 pharmacy claim for an ACE inhibitor or ARB, 725 (63.9%) for a beta-blocker, and 710 (62.6%) for a statin during the 3-month follow-up period; receipt of at least 1 prescription in all 3 classes was found in 339 (29.9%) of patients. Patients who were aged less than 45 years, 65-79 years, and e 80 years were significantly less likely than patients aged 45-64 years to receive statins (P less than 0.05). In addition, patients who were aged e 80 years were significantly less likely to receive ACE inhibitors/ARBs (P = 0.003), beta-blockers (P less than 0.001), or all 3 classes (P = 0.002). Women were less likely than men to receive statins (P = 0.004) and all 3 drug classes (P = 0.012). Patients with intermediate coronary syndrome were significantly less likely than those with acute myocardial infarction to receive any of the study drugs (P less than 0.001). Those patients who had used ACE inhibitors/ARBs, beta-blockers, statins, and all 3 drug classes during the 6 months prior to the index diagnosis of ACS were more likely than those without prior use (odds ratios of 12.2, 9.4, 8.3, and 4.9, respectively, P less than 0.001) to have these medications continued after ACS diagnosis. CONCLUSIONS: At 3 months following the index ACS hospitalization, the majority of the patients were not receiving the 3 guideline medication therapies. ACS patients with intermediate coronary syndrome and those aged 80 years or older were less likely to be receiving any of the 3 therapies, and women were less likely than men to receive statin therapy.