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 mortality of beta-blocker therapy for the treatment of acute myocardial infarction (AMI) in elderly diabetic patients and to examine whether beta-blocker therapy was associated with increased rates of hospital readmission for diabetic complications traditionally associated with beta-blockers.

BACKGROUND

Although many randomized trials have demonstrated that beta-blockers are effective in reducing mortality after AMI, some experts are concerned about the use of beta-blockers in diabetic patients. Little is known about 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 Cooperative Cardiovascular Project, which contained data abstracted from hospital medical records of Medicare beneficiaries admitted with an AMI during 1994 and 1995.

RESULTS

Out of 45,308 patients without contraindications to beta-blocker therapy, 7.4% were insulin-treated diabetics and 18.5% were non-insulin-treated diabetics. Beta-blockers were prescribed at discharge for 45% of insulin-treated diabetics, 48.1% of non-insulin-treated diabetics and 51% of nondiabetics (p < 0.001). After adjusting for demographic and clinical factors, diabetics continued to be less likely to receive beta-blockers at discharge compared with nondiabetics (odds ratio [OR] for insulin-treated diabetics 0.88, 95% confidence interval [CI] 0.82 to 0.96; OR for non-insulin-treated diabetics 0.93, 95% CI 0.88 to 0.98). After adjusting for potential confounders, beta-blockers were associated with lower one-year mortality for insulin-treated diabetics (hazard ratio [HR] = 0.87, 95% CI 0.72 to 1.07), non-insulin-treated diabetics (HR = 0.77, 95% CI 0.67 to 0.88) and nondiabetics (HR = 0.87, 95% CI 0.80 to 0.94). Beta-blocker therapy was not significantly associated with increased six-month readmission rates for diabetic complications among diabetics and nondiabetics.

CONCLUSIONS

Beta-blockers are associated with a lower one-year mortality rate for elderly diabetic patients to a similar extent as for nondiabetics, without increased risk of readmission for diabetic complications. Increasing the use of beta-blockers in elderly diabetic patients represents an opportunity to improve the care and outcomes of these patients after AMI.