25‑hydroxyvitamin D and physical and cognitive performance in older people with chronic conditions

INTRODUCTION Recently, the relationship between vitamin D deficiency and various pathologies as well as functional decline has been reported. 
OBJECTIVES The aim of the study was to assess the relationship between 25‑hydroxyvitamin D, 25(OH)D, levels and functional status in elderly patients. 
PATIENTS AND METHODS Mean age of 140 participants (women, 67.1%) was 79.64 ±6.99 years. The study had a cross‑sectional design. Physical performance was measured using the handgrip strength, Timed Up and Go, single‑leg stance, and tandem stance tests, as well as a balance platform. Cognition was evaluated with the Abbreviated Mental Test Score (AMTS), while functional status with the Basic Activities of Daily Living (ADL) and Instrumental Activities of Daily Living (IADL) scales. Plasma 25(OH)D levels were measured. 
RESULTS Less able patients (worse results in all tests) had significantly lower 25(OH)D levels. Subjects with 25(OH)D levels within the 3rd tertile had a higher AMTS score and handgrip strength; they swayed less on the balance platform and performed better in the IADL. In multivariate logistic regression analysis, 25(OH)D levels of 23.26–47.75 nmol/l were associated with increased odds of cognitive impairment (odds ratio [OR], 3.17; 95% confidence interval [CI], 1.04–9.68; P = 0.04), but also with less lateral sway (OR, 0.24; 95% CI, 0.09–0.64; P = 0.005). Plasma 25(OH)D levels above 47.75 nmol/l were associated with better performance in the tandem stance test (OR, 0.14; 95% CI, 0.04–0.52; P = 0.003) and further decreased lateral sway (OR, 0.27; 95% CI, 0.10–0.77; P = 0.01). 
CONCLUSIONS In elderly people with comorbid conditions, 25(OH)D levels were not associated with handgrip strength, but were associated with balance and cognitive function. These associations as well as high prevalence of vitamin D deficiency necessitate further research evaluating the effect of vitamin D supplementation on the functional status in elderly people.