Context: Decreased calcitriol production due to impaired renal function may be a significant risk factor for falls in normal aging population.

Objective: To examine the association between creatinine clearance (CrCl) and the incidence of falls and fallers in groups treated with placebo, calcitriol, hormone therapy (ET/HT) and calcitriol+ET/HT.

Design: 3 yr double blind placebo controlled study designed to test the efficacy of calcitriol and ET/HT on bone loss and falls. Analysis by intention to treat and post hoc.

Setting: Academic outpatient center.

Participants: 489 normal elderly women aged 65-77 yr. 415 women completed the study.

Intervention: Subjects were randomized to placebo, calcitriol 0.25mcg bid, ET/HT daily (conjugated equine estrogens 0.625 mg with or without medroxyprogesterone acetate 2.5 mg) and calcitriol+ET/HT.

Main outcome measures: Cumulative number of falls and fallers were compared between groups with 24 h urine CrCl<60 and 60ml/min.

Results: Calcitriol treatment decreased the number of fallers and falls. Low CrCl<60ml/min was a predictor of the number of falls per person but not fallers in the placebo group (P = 0.007). In the low CrCl group (<60ml/min), the rate of falls decreased on calcitriol by 53 percent (95%CI: -71% to -22%; P = 0.003), on calcitriol +ET/HT by 61 percent (95%CI: -76% to -37%; P = 0.001) and on ET/HT by 25 percent (95%CI: -55% to +24%; not significant). Calcitriol reduced the rate of falls by 30% (95%CI: -49% to -4%; P = 0.027) in the CrCl60ml/min group.

Conclusion: Calcitriol treatment decreases falls in all subjects but especially in elderly women with decreased renal function (<60ml/min) and in frequent fallers.