==== Front
Innov Aging
Innov Aging
innovateage
Innovation in Aging
2399-5300 Oxford University Press US 

10.1093/geroni/igaa057.2737
igaa057.2737
Abstracts
Session 7070 (Symposium)
AcademicSubjects/SOC02600
Design and Main Results of STURDY: A Randomized Clinical Trial of Four Vitamin D3 Doses to Prevent Falls in Older Adults
Appel Lawrence 1 Schrack Jennifer 2 Michos Erin 3 Mitchell Christine 2 Juraschek Stephen 4 Miller Edgar 3 Roth David 5 1 
Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
2 
Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States
3 
Johns Hopkins School of Medicine, Baltimore, Maryland, United States
4 
Harvard Medical School, Boston, Massachusetts, United States
5 
Johns Hopkins University, Baltimore, Maryland, United States
2020 
16 12 2020 
16 12 2020 
4 Suppl 1 Program Abstracts from The GSA 2020 Annual Scientific Meeting “Turning 75: Why Age Matters”759 759
© The Author(s) 2020. Published by Oxford University Press on behalf of The Gerontological Society of America.2020This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.Abstract
STURDY was a Bayesian, response-adaptive trial with dose-finding and confirmatory stages. Participants (n=688; ≥70years with serum 25(OH)D of 10-29ng/mL) were randomized to 200 (control), 1000, 2000, or 4000 IU/day of vitamin D3. The primary outcome was time to first fall or death over 2 years. During dose-finding, the best non-control dose was determined to be 1000IU/day based on higher primary outcome event rates in the 2000 and 4000IU/day doses than the 1000IU/day dose (posterior probability of being best dose=0.90; hazard ratios[HR] were 1.86 [95%CI: 1.16-2.97] and 1.68 [95%CI: 1.05-2.69], respectively). Participants were then switched from other non-control doses to 1000IU/day, and event rates did not differ between the pooled higher doses and control groups (HR=1.02, P=0.84). There was no heterogeneity by baseline 25(OHD). In conclusion, high-dose vitamin D supplementation ≥1000IU/day did not prevent falls. Whether vitamin D doses >2000IU/day increase the risk of falls is uncertain.