Beta-blocker therapy for secondary prevention of myocardial infarction in elderly diabetic patients - Results from the National Cooperative Cardiovascular Project

OBJECTIVES: We sought to determine the use and association with one-year mo rtality of beta-blocker therapy for the treatment of acute myocardial infar ction (AMI) in elderly diabetic patients and to examine whether beta-blocke r therapy was associated with increased rates of hospital readmission for d iabetic complications traditionally associated with beta-blockers. BACKGROUND: Although many randomized trials have demonstrated that beta-blo ckers are effective in reducing mortality after AMI, some experts are conce rned about the use of beta-blockers in diabetic patients. Little is known a bout the effectiveness and complication rate of beta-blocker therapy after AMI for elderly diabetics in community practice settings. METHODS: We conducted a retrospective cohort study using the National Coope rative Cardiovascular Project, which contained data abstracted from hospita l medical records of Medicare beneficiaries admitted with an AMI during 199 4 and 1995. RESULTS: Out of 45,308 patients without contraindications to beta-blocker t herapy, 7.4% were insulin-treated diabetics and 18.5%, were non-insulin-tre ated diabetics. Beta-blocker; were prescribed at discharge for 45% of insul in-treated diabetics, 48.1% of non-insulin-treated diabetics and 51% of non diabetics (p < 0.001). After adjusting for demographic and clinical factors , diabetics continued to be less likely to receive beta-blockers at dischar ge compared with nondiabetics (odds ratio [OR] for insulin-treated diabetic s 0.88, 95% confidence interval [CI] 0.82 to 0.96; OR for non-insulin-treat ed diabetics 0.93, 95% CI 0.88 to 0.98). after adjusting for potential conf ounders, beta-blockers were associated with lower one-year mortality for in sulin-treated diabetics (hazard ratio [HR] = 0.87, 95% CI 0.72 to 1.07), no n-insulin-treated diabetics (HR = 0.77, 95% CI 0.67 to 0.88) and nondiabeti cs (HR = 0.87, 95% CI 0.80 to 0.93). Beta-blocker therapy was not significa ntly associated with increased six-month readmission rates for diabetic com plications among diabetics and nondiabetics. CONCLUSIONS: Beta-blockers are associated with a lower one-year mortality r ate for elderly diabetic patients to a similar extent as for nondiabetics, without increased risk of readmission for diabetic complications. Increasin g the use of beta-blockers in elderly diabetic patients represents an oppor tunity to improve the care and outcomes of these patients after AMI. (C) 19 99 by the American College of Cardiology.