Myocardial infarction risk among patients with fractures receiving bisphosphonates

Abstract

Objective: To determine if bisphosphonates are associated with reduced risk of acute myocardial infarction (AMI).

Patients and methods: A cohort of 14,256 veterans 65 years or older with femoral or vertebral fractures was selected from national administrative databases operated by the US Department of Veterans Affairs and was derived from encounters at Veterans Affairs facilities between October 1, 1998, and September 30, 2006. The time to first AMI was assessed in relationship to bisphosphonate exposure as determined by records from the Pharmacy Benefits Management Database. Time to event analysis was performed using multivariate Cox proportional hazards regression. An adjusted survival analysis curve and a Kaplan-Meier survival curve were analyzed.

Results: After controlling for atherosclerotic cardiovascular disease risk factors and medications, bisphosphonate use was associated with an increased risk of incident AMI (hazard ratio, 1.38; 95% CI, 1.08-1.77; P=.01). The timing of AMI correlated closely with the timing of bisphosphonate therapy initiation.

Conclusion: Our observations in this study conflict with our hypothesis that bisphosphonates have antiatherogenic effects. These findings may alter the risk-benefit ratio of bisphosphonate use for treatment of osteoporosis, especially in elderly men. However, further analysis and confirmation of these findings by prospective clinical trials is required.

Keywords: AMI; BMD; HR; ICD-9-CM; International Classification of Diseases, Ninth Revision, Clinical Modification; NCBP; VA; Veterans Affairs; acute myocardial infarction; bone mineral density; hazard ratio; nitrogen-containing bisphosphonate.