Higher-dose vitamin D did not improve fall prevention, study finds
Elderly patients at high risk for falls who received 1,000 IU of a vitamin D supplement per day actually had higher risk of falls that were serious or required hospitalization than those who took 200 IU.
Vitamin D3 supplementation at doses of 1,000 IU per day or higher did not prevent falls compared with 200 IU per day in older patients with elevated fall risk and low serum vitamin D levels, a study found.
To compare the effects of four doses of vitamin D3 supplements on falls, researchers conducted a two-stage Bayesian, response-adaptive, randomized trial among 688 participants ages 70 years and older who had elevated fall risk and a serum 25-hydroxyvitamin D [25-(OH)D] level of 25 to 72.5 nmol/L. The study's primary outcome was time to first fall or death within two years. The study was funded by the National Institute on Aging and was published by Annals of Internal Medicine on Dec. 8.
For a dose-finding stage, participants were randomly assigned to a control dose of 200 IU per day, then 1,000, 2,000, or 4,000 IU per day. During the dose-finding stage, the primary outcome rates were higher for the 2,000- and 4,000-IU doses than for the 1,000-IU dose, which was selected as the best dose (posterior probability of being best, 0.90). After dose finding, participants assigned to receive noncontrol doses received the best dose, and new enrollees were randomly assigned to receive 200 IU/d or the best dose.
In the confirmatory stage, event rates were not significantly different between participants receiving the best dose of 1,000 IU (n=308) and those randomly assigned to receive 200 IU (n=339) (hazard ratio [HR], 0.94; 95% CI, 0.76 to 1.15; P=0.54). Analysis of falls with adverse outcomes suggested greater risk in the best-dose group versus the 200-IU group (HRs 1.87 [95% CI, 1.03 to 3.41] for serious falls and 2.48 [95% CI, 1.13 to 5.46] for falls with hospitalization).
Limitations of the study include that the control group received 200 IU per day of vitamin D3 and not a placebo and that dose finding ended before the prespecified thresholds for dose suspension and dose selection were reached, the researchers noted. They also noted that several analyses raised safety concerns about doses of 1,000 IU or higher, and that given its widespread use, policymakers should re-evaluate the upper dose limit considered safe.
An accompanying editorial stated, “This interesting, innovative trial reinforces some of what we know, highlights what we still do not know, and underscores what we need to learn.”