Sex-specific 25-hydroxyvitamin D threshold concentrations for functional outcomes in older adults: PRoject on Optimal Vitamin D in Older adults (PROVIDO)

摘要

Background: Threshold serum 25-hydroxyvitamin D [25(OH)D] concentrations for extraskeletal outcomes are uncertain and could differ from recommendations (20-30 ng/mL) for skeletal health. Objectives: We aimed to identify and validate sex-specific threshold 25(OH)D concentrations for older adults' physical function. Methods: Using 5 large prospective, population-based studies-Age, Gene/Environment Susceptibility-Reykjavik (n = 4858, Iceland): Health. Aging, and Body Composition (n = 2494, United States); Invecchiare in Chianti (n = 873, Italy): Osteoporotic Fractures in Men (n = 2301, United States); and Study of Osteoporotic Fractures (n = 5862, United States)-we assessed 16,388 community-dwelling adults (10,376 women, 6012 men) aged >= 65 y. We analyzed 25(OH)D concentrations with the primary outcome (incident slow gait: women = 24.0 ng/mL in women (RR: 1.29; 95% CI: 1.10, 1.50) and 25(OH)D = 21.0 ng/mL in men (RR: 1.43; 95% CI: 1.01, 2.02). Most associations between 25(OH)D and secondary outcomes were modest; estimates were similar between validation and training datasets. Conclusions: Empirically identified and validated sex-specific threshold 25(OH)D concentrations for physical function for older adults, 24.0 ng/mL for women and 21.0 ng/mL for men, may inform candidate reference concentrations or the design of vitamin D intervention trials.