Greater daily defined dose of antihypertensive medication increases the risk of falls in older people--a population-based study

Abstract

Objectives: To determine whether there is a relationship between daily defined dose (DDD) of antihypertensive drugs and the risk of falls.

Design: Prospective population-based cohort study.

Setting: Tasmanian Study of Cognition and Gait, Australia.

Participants: Participants aged 60 to 86 randomly selected from the electoral roll.

Measurements: Antihypertensive dose was quantified by estimating DDD, allowing standardized comparison of dosage between drug classes. Falls were identified prospectively over 12 months. The relative risk (RR) of falls associated with DDD was estimated using log binomial regression adjusting for age, sex, body mass index, education, cardiovascular history, and other risk factors for falls.

Results: Participants (N=409) had a mean age of 72.0±6.9, and 56% were male. Mean baseline blood pressure was 142/80 mmHg, and 54% were taking antihypertensive medications. One hundred sixty-one participants (39%) fell over the 12 months. Those who fell were on a higher DDD of antihypertensives (1.51±2.16 than those who did not (1.03±1.42) (P=.007). Higher DDD was independently associated with greater fall risk (RR=1.07, 95% confidence interval (CI)=1.02-1.11; P=.004), with a 48% greater risk in those with a DDD of more than 3 (RR=1.48, 95% CI=1.06-2.08; P=.02), particularly in those with a history of stroke (P for interaction .01). This effect remained even after excluding those not taking antihypertensives or stratifying according to presence of hypertension and medication use.

Conclusion: Higher dose of antihypertensive medication is independently associated with falls in older people, particularly in those with a history of previous stroke, and with more than three standard units conferring the highest risk.

Keywords: antihypertensive medication; falls; older people.