Endocrine and inflammatory markers as predictors of frailty

Objective To examine the association of serum concentrations of 25-hydroxyvitamin D [25(OH)D], interleukin-6 (IL-6), C-reactive protein (CRP) and IGF-1 with prevalent and incident frailty. Design The Longitudinal Aging Study Amsterdam (LASA), a prospective cohort study with 3-yearly measurement cycles. Setting General population-based sample. Participants The respondents were men and women aged 65 and over, who participated at T-1 (1995/1996, N = 1720) and T-2 (1998/1999, N = 1509). Blood samples were obtained at T-1 (N = 1271). Measurements The presence of frailty at T-1 and 3-year incidence of frailty. Frailty is defined as the presence of three out of nine frailty indicators. Results At T-1, 242 (19.0%) of all respondents were frail. Those who were frail at T-1 had higher CRP and lower 25(OH)D levels. Serum 25(OH)D remained associated with frailty after adjustment for potential confounders with an odd ratios (OR) of 2.60 [95% confidence interval (95% CI) 1.60-4.21] for 25(OH)D < 25 nmol/l and 1.72 (95% CI 1.19-2.47) for 25(OH)D 25-50 nmol/l vs. high levels of 25(OH)D. Of the nonfrail at T-1, 125 respondents (14.1%) became frail at T-2. After adjustment, moderately elevated CRP levels (3-10 mu g/ml) (OR 1.69, 95% CI 1.09-2.63) and low 25(OH)D (OR 2.04, 95% CI 1.01-4.13) were associated with incident frailty. No consistent associations were observed for IL-6 and IGF-1. Conclusion Low 25(OH)D levels were strongly associated with prevalent and incident frailty; moderately elevated levels of CRP were associated with incident frailty.