The association of frailty with serum 25-hydroxyvitamin D and parathyroid hormone levels in older European men

Background: the link between the vitamin D endocrine axis and frailty remains undefined, with few studies examining the joint effect of vitamin D and parathyroid hormone (PTH) levels. Our objective was to determine the association of frailty with serum 25-hydroxyvitamin D (25(OH) D) and PTH. Setting: cross-sectional analysis within the European Male Ageing Study (EMAS). Participants: a total of 1,504 community-dwelling men aged 60-79 years. Methods: frailty was classified using a frailty phenotype (FP) and frailty index (FI). The association of frailty with 25(OH)D and PTH was examined using multinomial logistic regression; individual FP criteria with 25(OH)D and PTH using binary logistic regression. Results were expressed as relative odds ratios (ROR) and 95% confidence intervals (CIs) for multinomial; odds ratios (OR) and 95% CIs for binary models. Results: using the FP, 5.0% of subjects were classified as frail and 36.6% as prefrail. Lower levels of 25(OH)D were associated with being prefrail (per 1 SD decrease: ROR = 1.45; 95% CI: 1.26-1.67) and frail (ROR = 1.89; 95% CI: 1.30-2.76), after adjusting for age, centre and health and lifestyle confounders (robust group = base category). Higher levels of PTH were associated with being frail after adjustment for confounders (per 1 SD increase: ROR = 1.24; 95% CI: 1.01-1.52). Comparable results were found using the FI. Among the five FP criteria only sarcopenia was not associated with 25(OH)D levels, while only weakness was associated with PTH. Conclusion: lower 25(OH)D and higher PTH levels were positively associated with frailty in older men. Prospective data would enable the temporal nature of this relationship to be explored further.