OBJECTIVES:

To study the effect of alfacalcidol (1alpha(OH)D3) on fall risk in community-dwelling elderly men and women.

DESIGN:

Randomized, double-blind, placebo-controlled intervention trial.

SETTING:

Basel, Switzerland.

PARTICIPANTS:

Three hundred seventy-eight community-dwelling elderly (191 women/187 men).

INTERVENTION:

Participants were randomly assigned to receive 1 microg of alfacalcidol or matched placebo daily for 36 weeks.

MEASUREMENTS:

Serum 25-hydoxyvitamin D3 (25(OH) D,1,25-dihydroxyvitamin D3 (D-hormone), and intact parathormone (iPTH) levels were measured using radioimmunoassay at baseline and every 12 weeks. Numbers of fallers and falls were assessed using a questionnaire during each study site visit. Dietary calcium intake was assessed at baseline using a food frequency questionnaire.

RESULTS:

At baseline, participants had, on average, normal vitamin D and D-hormone serum levels. Over 36 weeks, alfacalcidol treatment was associated with fewer fallers (odds ratio (OR)=0.69, 95% confidence interval (CI)=0.41-1.16) than placebo. In a post hoc subgroups analysis by medians of total calcium intake, this reduction reached significance in alfacalcidol-treated subjects with a total calcium intake of more than 512 mg/d (OR=0.45, 95% CI=0.21-0.97, P=.042) but not in those who consumed less than 512 mg/d (OR=1.00, 95% CI= 0.47-2.11, P=.998). Alfacalcidol treatment was also, independent of total calcium intake, associated with a significant 37.9% reduction in iPTH serum levels (P<.0001). No cases of clinically relevant hypercalcemia were observed.

CONCLUSION:

Provided a minimal calcium intake of more than 512 mg/d, alfacalcidol treatment significantly and safely reduces number of fallers in an elderly community dwelling population.