Association of serum vitamin D with frailty in older Korean adults.

Objectives: The association between serum levels of vitamin D and frailty in older Korean adults was examined.

Study Design: Cross-sectional study. Older people living in the community across 10 study centers throughout South Korea. The baseline data (2016-2017) of 2872 participants aged 70-84 years in the Korean Frailty and Aging Cohort Study were evaluated.

Main Outcome Measures: Serum vitamin D level was assessed with an electro-chemiluminescence immunoassay. Frailty was defined using Fried's frailty index. A multinomial logistic regression analysis was used to examine the association between serum levels of vitamin D and frailty.

Results: The percentages of those with serum vitamin D levels of <25 nmol/L, 25-49 nmol/L, 50-74 nmol/L, and ≥75 nmol/L were 4.1 %, 37.0 %, 37.8 %, and 21.0 %, respectively. The prevalence of frailty was 9.7 %. Those with lower serum vitamin D levels, compared with ≥75 nmol/L, tended to have higher odds of being frail than being non-frail (OR: 1.58, 95 % CI: 1.05-2.39 for 50-74 nmol/L; OR: 1.49, 95 % CI: 0.98-2.26 for 25-49 nmol/L; OR: 1.37, 95 % CI: 0.65-2.88 for <25 nmol/L). Among the components of frailty, low grip strength was significantly associated with lower serum levels of vitamin D.

Conclusions: Low serum levels of vitamin D are associated with an increased likelihood of frailty in community-dwelling older adults, suggesting a potentially protective role of vitamin D against frailty.