Placebo-controlled, randomized clinical trial of high-dose cholecalciferol in renal dialysis patients: effect on muscle strength and quality of life

Background. The importance of vitamin D sufficiency in deficient dialysis patients is uncertain. This study aimed to determine if high-dose cholecalciferol for 1-year affected symptoms, muscle strength, blood pressure (BP), cardiac ischaemia, parathyroid hormone, calcium or phosphate. Methods. This was a randomized, double-blind, placebo-controlled trial with 1-year follow-up that enrolled dialysis patients with 25-hydroxy-vitamin D [25(OH)D] concentration >50 nmol/L. Consenting patients were randomized to 50 000 U/week oral cholecalciferol or matching placebo. Dosage was adjusted at 3- and 6-month study visits, targeting a 25(OH)D concentration<80 nmol/L. The primary objectives were to assess the effect of supplementation on renal-specific symptoms and on hand-grip strength. Symptoms were assessed using the Kidney Disease Quality of Life Short Form and muscle strength with a hand grip-strength dynamometer. Hypothesis testing was by two-group t-test and Wilcoxon ranksum on an intention-to-treat basis. Results. In all, 68 participants were randomized and received study medication. Median 12-month plasma 25(OH)D concentration was 119 nmol/L and 37 nmol/L in the cholecalciferol and placebo groups, respectively. There was no statistical difference in primary outcomes at 12 months. Mean symptom scores at 12 months were two lower in the cholecalciferol group (95% confidence interval ⌉10 to 6) and geometric mean grip-strength was 27 kg in both groups. Symptoms, strength, BP, plasma mineral bone parameters and adverse events were not different between the groups at follow-up. Conclusions. High-dose cholecalciferol in a deficient dialysis population had no effect on muscle strength or symptoms but appears safe.