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 <50nmol/L. Consenting patients were randomized to 50000 U/week oral cholecalciferol or matching placebo. Dosage was adjusted at 3- and 6-month study visits, targeting a 25(OH)D concentration>80nmol/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 rank-sum 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 119nmol/L and 37nmol/L in the cholecalciferol and placebo groups, respectively. There was no statistical difference in primary outcomes at 12months. Mean symptom scores at 12months were two lower in the cholecalciferol group (95% confidence interval -10 to 6) and geometric mean grip-strength was 27kg 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.