National use and effectiveness of beta-blockers for the treatment of elderly patients after acute myocardial infarction: National Cooperative Cardiovascular Project

Abstract

Context: Despite the importance of beta-blockers for secondary prevention after acute myocardial infarction (AMI), several studies have suggested that they are substantially underutilized, particularly in older patients.

Objectives: To describe the contemporary national pattern of beta-blocker prescription at hospital discharge among patients aged 65 years or older with an AMI, to identify the most important predictors of the prescribed use of beta-blockers at discharge, and to determine the independent association between beta-blockers at discharge and mortality in clinical practice.

Design: Retrospective cohort study using data created from medical charts and administrative files.

Setting: Acute care nongovernmental hospitals in the United States.

Patients: National cohort of 115015 eligible patients aged 65 years or older who survived hospitalization with a confirmed AMI in 1994 or 1995.

Main outcome measures: Blocker as a discharge medication and mortality in the year after discharge.

Results: Among the 45308 patients without contraindications to beta-blockers, 22665 (50.0%) had a beta-blocker as a discharge medication. There was significant variation by state, ranging from 30.3% to 77.1 %. Of the 36795 patients who were not receiving beta-blocker therapy on admission, 16006 (43.5%) had therapy initiated on or before discharge. Demographic and clinical variables explained relatively little of the variation in the initiation of beta-blocker therapy. The prescribed use of calcium channel blockers at discharge had a strong negative association with the use of beta-blockers (odds ratio [OR] of beta-blocker use, 0.25; 95% confidence interval [CI], 0.24-0.26). The New England region had significantly higher use of beta-blocker therapy than the rest of the country. Compared with cardiologists, internists had similar rates (OR, 0.94; 95% CI, 0.90-1.00) and general and family practice physicians had lower rates (OR, 0.78; 95% CI, 0.73-0.83). After adjusting for potential confounders, beta-blockers were associated with a 14% lower risk of mortality at 1 year after discharge. The association with lower mortality was present in subgroups stratified by age, sex, and left ventricular ejection fraction.

Conclusions: Many ideal patients for beta-blocker therapy are not prescribed these drugs at discharge following AMI. The clinical and demographic characteristics of the patients do not explain much of the variation in the treatment pattern. Geographic factors and physician specialty are independently associated with the decision to use beta-blockers. Elderly patients who are prescribed beta-blockers at discharge have a better survival rate, consistent with the findings of randomized controlled trials of younger and lower-risk populations.