Serum 25-hydroxyvitamin D and physical function in older adults: the Cardiovascular Health Study All Stars.

Abstract

To examine the association between 25-hydroxyvitamin D (25(OH)D) and physical function in adults of advanced age. Cross-sectional and longitudinal analysis of physical function over 3years of follow-up in the Cardiovascular Health Study All Stars. Forsyth County, North Carolina; Sacramento County, California; Washington County, Maryland; and Allegheny County, Pennsylvania. Community-dwelling adults aged 77 to 100 (N=988). Serum 25-hydroxyvitamin D 25(OH)D), Short Physical Performance Battery (SPPB), and grip and knee extensor strength assessed at baseline. Mobility disability (difficulty walking half a mile or up 10 steps) and activities of daily living (ADLs) disability were assessed at baseline and every 6months over 3years of follow-up. Almost one-third (30.8%) of participants were deficient in 25(OH)D (<20ng/mL). SPPB scores were lower in those with deficient 25(OH)D (mean (standard error) 6.53(0.24)) than in those with sufficient 25(OH)D (≥30ng/mL) (7.15(0.25)) after adjusting for sociodemographic characteristics, season, health behaviors, and chronic conditions (P=.006). Grip strength adjusted for body size was also lower in those with deficient 25(OH)D than in those with sufficient 25(OH)D (24.7(0.6)kg vs 26.0(0.6)kg, P=.02). Participants with deficient 25(OH)D were more likely to have prevalent mobility (OR=1.44, 95% confidence interval (CI))=0.96-2.14) and ADL disability (OR=1.51, 95% CI=1.01-2.25) at baseline than those with sufficient 25(OH)D. Furthermore, participants with deficient 25(OH)D were at greater risk of incident mobility disability over 3years of follow-up (hazard ratio=1.56, 95% CI=1.06-2.30). Vitamin D deficiency was common and was associated with poorer physical performance, lower muscle strength, and prevalent mobility and ADL disability in community-dwelling older adults. Moreover, vitamin D deficiency predicted incident mobility disability.