Association between 25-hydroxyvitamin D, somatic muscle weakness and falls risk in end-stage renal failure

Objective Suboptimal levels of 25-hydroxyvitamin D (25OHD) are common in haemodialysis patients (Chronic Kidney disease-5D: CKD-5D) and may be associated with reduced muscle strength and increased falls risk. We tested the hypothesis that 25OHD levels may be independently associated with falls risk in CKD-5D. Background Supplementation with calcium and cholecalciferol reduces hip and other nonvertebral fractures in elderly individuals, and this effect may in part be attributable to reduction in falls frequency. The relationship between 25OHD and falls risk has not been investigated in CKD-5D. Design and Patients This is a cross-sectional study of 25 CKD-5D patients with predialysis 25OHD, 1,25-dihydroxyvitamin D (1,25(OH)(2)D) and intact parathyroid hormone (iPTH) measurement. Falls risk was assessed by quadriceps muscle strength, FallsScreen(C) test (FST), Berg Balance Scale (BBS), timed 'up and go' (TUG) test, Modified Barthel Index (MBI) and Falls Efficacy Scale (FES). Results Mean age was 69 center dot 8 +/- 12 center dot 1 years, and median time on dialysis was 3 center dot 1 years. Median 25OHD level was 55 center dot 3 nmol/l (range 20 center dot 8-125 center dot 8 nmol/l). Muscle strength was significantly positively correlated with 25OHD (P = 0 center dot 024) but not with 1,25(OH)(2)D (P = 0 center dot 477) or PTH (P = 0 center dot 461). Statistically significant correlation between 25OHD levels and FST (P = 0 center dot 028) plus MBI (P = 0 center dot 0046) was noted. No significant correlation was detected between falls risk and 1,25(OH)(2)D or PTH. Conclusions Suboptimal levels of 25OHD in CKD-5D are associated with reduced quadriceps muscle strength and increased falls risk. 25OHD may be more important than the active renal metabolite 1,25(OH)(2)D for muscle strength with implications for vitamin D choice and goals of supplementation. Further investigation is required to examine effectiveness of calciferol supplementation on the incidence of falls in CKD-5D.