Low serum concentrations of 25-hydroxyvitamin D in older persons and the risk of nursing home admission

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Abstract
Background: The prevalence of vitamin D deficiency in nursing home patients is high. Objective: We aimed to ascertain whether lower serum 25-hydroxyvitamin D [25(OH)D] concentrations increase the risk of future nursing home admission and early death. Design: We included 1260 independent, community-dwelling persons aged ≥65 y who were participating in the Longitudinal Aging Study Amsterdam (1995–1996). Study outcomes were time to nursing home admission during 6 y of follow-up and time to death until 1 April 2003. Results: Vitamin D deficiency [25(OH)D < 25 nmol/L] and insufficiency [25(OH)D = 25–49.9 nmol/L] were present in 127 (10.1%) and 462 (36.7%) subjects, respectively. During follow-up, 138 subjects (11.0%) were admitted to nursing homes, and 380 subjects (30.2%) died. The risk of nursing home admission for participants with 25(OH)D deficiency was 53 cases per 1000 person-years higher than that for those with high 25(OH)D (≥75 nmol/L) concentrations (58 compared with 5 cases). After adjustment for potential confounders, the hazard ratio (95% CI) of nursing home admission was 3.48 (1.39, 8.75) for vitamin D–deficient, 2.77 (1.17, 6.55) for vitamin D–insufficient, and 1.92 (0.79, 4.66) for vitamin D–borderline persons as compared with persons with high 25(OH)D (P for trend = 0.002). The results remained after additional adjustment for frailty indicators. Lower 25(OH)D was associated with higher mortality risk, but this association was not significant after adjustment for frailty indicators. Conclusion: Lower serum 25(OH)D concentrations in older persons are associated with a greater risk of future nursing home admission and may be associated with mortality.