Association Between Vitamin D, Frailty, and Progression of Frailty in Community-Dwelling Older Women

Context: Vitamin D (25OHD) is involved in many physiological functions that decline with age, contributing to frailty and increased risk for negative health outcomes. Whether 25OHD is a long-term risk marker for frailty over a longer time and whether it is consistent with advancing age is unclear. Objective: To investigate the association between 25OHD and frailty in older women followed for 10 years. Design and Setting: Prospective, population-based, cohort study in Malmo, Sweden. Participants: Community-dwelling women, age 75 years (N = 1044) with reassessments at ages 80 (n = 715) and 85 (n = 382) years. Methods: Frailty was quantified using a 10-variable frailty index. Women were categorized as 25OHD insufficient (<50 nmol/L) or sufficient (>= 50 nmol/L). Results: At ages 75 and 80 years, women with insufficient 25OHD were frailer than women with sufficient 25OHD (0.23 vs 0.18, P < 0.001; and 0.32 vs 0.25, P = 0.001, respectively). At age 80 years, 25OHD insufficiency was associated with subsequent frailty 5 years later (0.41 vs 0.32; P = 0.011). Accelerated progression of frailty was not associated with lower 25OHD levels, and 25OHD level.75 nmol/L was not additionally beneficial with regard to frailty. No association between 25OHD and frailty was observed at age 85 years. Within the frailty index, variables associated with 25OHD were related to muscle strength and function. Conclusion: In this study, 25OHD insufficiency was associated with increased frailty in all but the oldest old. This study supports the value of maintaining sufficient 25OHD levels for healthy aging.