Antihypertensive Drugs and Risk of Hip Fracture in the Elderly

Among adults 60 to 79 years of age, the prevalence of hypertension is >50%; in addition, 72% of patients ≥60 years of age who are newly diagnosed with hypertension take antihypertensive medication. The initiation of antihypertensive drugs (thiazide diuretics, angiotensin II converting-enzyme [ACE] inhibitors, angiotensin II receptor blockers [ARBs], calcium channel blockers, or beta-adrenergic blockers [BBs]) in this population has been associated with an immediate increased of falls, but it is not known whether this increased risk is accompanied by an immediate risk of hip fracture.

Researchers recently conducted a study to assess the association between initiating antihypertensive drugs and the immediate increase in risk of hip fracture in a large population of community-dwelling elderly persons. They reported study results in Archives of Internal Medicine [2012;172(22):1739-1744].

The primary study outcome measure was the first occurrence of a hip fracture from April 1, 2000, through March 31, 2009. The study was a population-based, self-controlled case series design utilizing healthcare administrative databases. To define the exposed cases, the fractures were linked to a cohort of newly treated hypertensive elderly patients.

The risk period was defined as the first 45 days after initiation of antihypertensive therapy; control periods were before and after treatment in a 450-day observation period. The analysis determined the relative incidence (incidence rate ratio [IRR]), defined as the hip fracture rate in the risk period compared with control periods.

The databases provided information on 301,591 newly treated hypertensive community-dwelling elderly patients. Of those, 1463 hip fractures were identified during the observation period. Mean age of the exposed cases was 81 years and most were women (80.7%). Patients with hip fractures were most likely to have been treated with an ACE inhibitor (30.1%), whereas ARBs were the least commonly used (4.4%) among the hip fracture group. The researchers noted that, “Only 6.0% of the exposed cases had a history of hip fracture.”

Those who started treatment for hypertension with an antihypertensive drug had a 43% increased risk of hip fracture during the first 45 days of treatment (IRR, 1.43; 95% confidence interval [CI], 1.19-1.72). The IRR estimates were consistent among the 5 classes of antihypertensive drugs; the ACT inhibitors and BBs demonstrated statistical significance (IRR, 1.53; 95% CI, 1.12-2.10 and IRR, 1.58; 95% CI, 1.01-2.48, respectively).

When the researchers subdivided the postexposure risk period, the analysis found that elderly patients who began treatment for hypertension with any antihypertensive drug had a 54% increased risk of hip fracture during the 15-44 day period (IRR, 1.54; 95% CI, 1.25-1.90). The increased trend was seen for all antihypertensive classes with the exception of thiazide diuretics; the increased trend was statistically significant for ACE inhibitors and BBs (IRR, 1.58; 95% CI, 1.09-2.29 and IRR, 2.08; 95% CI, 1.29-3.34, respectively).

The researchers cited limitations to the study: the database captured prescriptions only for patients ≥65 years of age and it is possible those patients were exposed to antihypertensive drugs at an earlier age.

In summary, the researchers said, “Antihypertensive drugs were associated with an immediate increased hip fracture risk during the initiation of treatment in hypertensive community-dwelling elderly patients. Caution is advised when initiating antihypertensive drugs in the elderly.”