Risk of fractures in older adults using antihypertensive medications

Abstract

Many medications used to control blood pressure have been associated with bone metabolism. In addition, hypertension itself may be associated with reduced bone mineral density. We examined the relative risk of fracture among subjects with hypertension initiating single-drug therapy for antihypertension treatment. We assembled a large cohort of Medicare beneficiaries with a diagnosis of hypertension who had not filled a prescription for an antihypertensive medication in the prior 365 days. All subsequently began treatment with a single antihypertensive drug. These subjects were followed forward using health care utilization data to determine the risk of a typical osteoporotic fracture. Adjusted Cox proportional hazards regression models were constructed to assess the relative risk of fracture across types of antihypertensive medications. We identified 376,061 eligible subjects. Fracture rate in the total cohort was 35.2 per 1000 person-years [95% confidence interval (CI) 34.4-36.1]. Rates varied significantly across type of antihypertensive, with thiazide diuretics having the lowest rate (28.5, 95% CI 25.4-31.9) and loop diuretics the highest rate (49.0, 95% CI 46.1-52.1). In models adjusting for relevant comorbidities and comedications accessible in health care utilization data, the risk of fracture was reduced in users of angiotensin receptor blockers [hazard ratio (HR) = 0.76, 95% CI 0.68-0.86) and thiazide diuretics (HR = 0.85, 95% CI 0.76-0.97) compared with calcium channel blockers. The adjusted fracture risk was not significantly different from the reference for loop diuretics, beta blockers, and angiotensin-converting enzyme (ACE) inhibitors. It is concluded that the risk of fracture differs across users of different antihypertensive medications.