BACKGROUND/OBJECTIVES: To assess whether vitamin D supplementation prevents specific fall subtypes and sequelae (e.g., fracture).

DESIGN

Secondary analyses of STURDY (Study to Understand Fall Reduction and Vitamin D in You)-a response-adaptive, randomized clinical trial.

SETTING

Two community-based research units.

PARTICIPANTS

Six hundred and eighty-eight participants ≥70 years old with elevated fall risk and baseline serum 25-hydroxyvitamin D levels of 10-29 ng/ml.

INTERVENTION

200 IU/day (control), 1000 IU/day, 2000 IU/day, or 4000 IU/day of vitamin D3.

MEASUREMENTS

Outcomes included repeat falls and falls that were consequential, were injurious, resulted in emergency care, resulted in fracture, and occurred either indoors or outdoors.

RESULTS

After adjustment for multiple comparisons, the risk of fall-related fracture was greater in the pooled higher doses (≥1000 IU/day) group compared with the control (hazard ratio [HR] = 2.66; 95% confidence interval [CI]:1.18-6.00). Although not statistically significant after multiple comparisons adjustment, time to first outdoor fall appeared to differ between the four dose groups (unadjusted p for overall difference = 0.013; adjusted p = 0.222), with risk of a first-time outdoor fall 39% lower in the 1000 IU/day group (HR = 0.61; 95% CI: 0.38-0.97; unadjusted p = 0.036; adjusted p = 0.222) and 40% lower in the 2000 IU/day group (HR = 0.60; 95%CI 0.38-0.97; p = 0.037; adjusted p = 0.222), each versus control.

CONCLUSION

Vitamin D supplementation doses ≥1000 IU/day might have differential effects on fall risk based on fall location and fracture risk, with the most robust finding that vitamin D doses between 1000 and 4000 IU/day might increase the risk of first time falls with fractures. Replication is warranted, given the possibility of type 1 error.