Monthly High-Dose Vitamin D Treatment for the Prevention of Functional Decline: A Randomized Clinical Trial

IMPORTANCE: Vitamin D deficiency has been associated with poor physical performance. OBJECTIVE: To determine the effectiveness of high-dose vitamin D in lowering the risk of functional decline. DESIGN, SETTING, AND PARTICIPANTS: One-year, double-blind, randomized clinical trial conducted in Zurich, Switzerland. The screening phase was December 1, 2009, to May 31, 2010, and the last study visit was in May 2011. The dates of our analysis were June 15, 2012, to October 10, 2015. Participants were 200 community-dwelling men and women 70 years and older with a prior fall. INTERVENTIONS: Three study groups with monthly treatments, including a low-dose control group receiving 24 000 IU of vitamin D3 (24 000 IU group), a group receiving 60 000 IU of vitamin D3 (60 000 IU group), and a group receiving 24 000 IU of vitamin D3 plus 300 μg of calcifediol (24 000 IU plus calcifediol group). MAIN OUTCOMES AND MEASURES: The primary end point was improving lower extremity function (on the Short Physical Performance Battery) and achieving 25-hydroxyvitamin D levels of at least 30 ng/mL at 6 and 12 months. A secondary end point was monthly reported falls. Analyses were adjusted for age, sex, and body mass index. RESULTS: The study cohort comprised 200 participants (men and women ≥70 years with a prior fall). Their mean age was 78 years, 67.0% (134 of 200) were female, and 58.0% (116 of 200) were vitamin D deficient (