Association of low 25-hydroxyvitamin D levels with the frailty syndrome in an aged population: results from the KORA-age Augsburg study

Older adults often suffer from vitamin D deficiency and from the frailty syndrome charac-terized by different physical limitations, complicating independent everyday life. Previous studies have suggested a relationship between vitamin D status and the frailty syndrome, but results have been partly inconsistent, particularly regarding the shape of the association. Therefore, our aim was to further assess the association of 25-hydroxyvitamin D (25(OH)D) serum levels and frailty in older participants.Cross-sectional population-based study.The study population included 478 men and 462 women of the KORA (COoperative health research in the Region of Augsburg)-Age study born before 1944 examined in 2009.Classification of participants into different frailty states was performed according to the following criteria: weight loss, exhaustion, physical inactivity, slowness, and weakness. PARTICIPANTS who met 1-2 or ≥ 3 of the 5 criteria were classified as prefrail or frail, respectively. Total 25(OH)D was measured in non-fasting serum samples with an enhanced chemiluminescence immunoassay. Sequential logistic regression models adjusted for age, sex, season, lifestyle factors, diseases and biomarkers including parathyroid hormone (PTH) were calculated.High levels of 25(OH)D were inversely associated with being prefrail (N=351) or frail (N=38) in the model adjusted for age, sex, season and lifestyle factors. Compared to levels15 ng/ml, odds ratios (ORs) (95% confidence intervals (CIs) were 0.52 (0.34-0.78) for levels of 15-20 ng/ml, 0.55 (0.37-0.81) for levels of 20-30 ng/ml and 0.32 (0.21-0.51) for levels ≥ 30 ng/ml. Additional adjustment for potential mediators including PTH only slightly attenuated these associations. For single frailty-components, significantly decreased ORs were found for exhaustion, physical inactivity and slowness comparing 25(OH)D levels ≥ 30 ng/ml with levels15 ng/ml.Subjects with 25(OH)D serum levels ≥ 15 ng/ml were less frequently prefrail or frail.