Beta-blockers may be linked to higher mortality risk in patients with diabetes, including those with heart failure, a recent study found.
Researchers used data from the 1999-2010 U.S. National Health and Nutrition Examination Survey to perform a prospective cohort study of patients with or without diabetes who were taking beta-blockers. Patients were followed from the time of their survey participation to Dec. 31, 2011. A Cox proportional hazards model was used to analyze all-cause mortality, and multivariate-adjusted hazard ratios (HRs) were compared for patients who were taking beta-blockers and those who were not. Study results were published online March 12 by Mayo Clinic Proceedings and appear in the April issue.
A total of 2,840 diabetic patients and 14,684 nondiabetic patients were included in the study. Among patients with diabetes, 697 were taking beta-blockers and 2,143 were not; among patients without diabetes, 1,584 were taking beta-blockers and 13,100 were not. Patients with diabetes who were taking any beta-blocker had a significantly higher risk for all-cause mortality versus patients with diabetes who were not taking a beta blocker (HR, 1.49; P=0.01). This increased mortality risk was also seen in diabetic patients taking a beta-1 selective beta-blocker (HR, 1.60; P=0.007) and in those taking a specific beta-blocker, that is, bisoprolol, metoprolol, or carvedilol (HR, 1.55; P=0.01).
Patients with diabetes and coronary heart disease who were taking beta-blockers had a significantly higher mortality risk than those not taking beta-blockers (HR, 1.64; P=0.02). However, nondiabetic patients with coronary heart disease who were taking beta-blockers had a significantly lower mortality risk versus patients who were not taking beta-blockers (HR, 0.68; P=0.02). Results were similar in a propensity score-matched analysis.
The researchers noted that their study was observational and may not be completely applicable to current practice, since it did not reflect the use of newly available treatments. They also pointed out that bias could have affected their results and that they could not account for medication adherence, among other limitations. However, they concluded that beta-blocker therapy appears to be associated with increased risk for all-cause mortality in patients with diabetes, including those who have coronary heart disease.
“Further studies are needed to assess whether beta-blockers are effective in reducing mortality and coronary events in diabetic patients receiving optimal medical treatment,” the authors wrote.
An accompanying editorial called the study “provocative” and its results “sobering.” They noted that evidence from trials of beta-blockers after myocardial infarction has been extended to other conditions without further research. Furthermore, they pointed out that the possible benefits of beta-blocker therapy have been greatly decreased by aggressive reperfusion therapy and that most patients with previous myocardial infarction take other drugs besides beta-blockers, such as aspirin, new oral anticoagulants, lipid-lowering drugs, and renin-angiotensin blockers.
The editorial authors wrote that they “wholeheartedly agree” with the study authors' call for prospective randomized trials of beta-blockers in diabetic patients. “Until then,” they wrote, “the only ironclad indication for cardioprotection with [beta]-blockers remains heart failure with reduced ejection fraction.”