The Effect of Niacinamide Supplementation on Phosphate Concentrations in Dutch Dialysis Patients: a randomised, crossover trial.

OBJECTIVE: Hyperphosphatemia is a common complication in patients with kidney failure, despite the use of phosphate binders (PBs). Vitamin B3, either in the form of niacin or niacinamide (NAM), shows potential as "add-on" treatment to reduce serum phosphate concentrations in this population. NAM seems to lack many of the side-effects that are observed with niacin. The aim of this study was to investigate whether NAM is an effective and acceptable treatment in reducing serum phosphate concentrations in patients with kidney failure.

METHODS: DiaNia was a double-blind placebo-controlled randomised crossover trial, comparing NAM (250-500 mg/day) to placebo as "add-on" treatment to an individual treatment with approved PBs for 12 weeks in patients receiving hemodialysis. The primary outcome was serum phosphate concentrations, and the secondary outcomes were platelet counts as well as drop-outs due to side-effects. Data was analysed using both per-protocol (PP) and intention-to-treat (ITT) analyses.

RESULTS: Mean age of the PP population (n=26) was 63.6 ± 17.2 years and 53.8% were men. NAM treatment significantly reduced serum phosphate with 0.59 mg/dL (p=0.03). Linear mixed models (LMMs) demonstrated superiority of 12 weeks NAM over 12 weeks placebo with a between-treatment difference of 0.77 mg/dL (95% CI 0.010, 1.43; p=0.03). Similar results, although not significant, were found in the ITT population. We found no between-treatment differences in platelet counts and during the NAM treatment we observed three drop-outs due to side effects (8.6%).

CONCLUSION: NAM is effective in reducing serum phosphate concentrations in patients with kidney failure receiving hemodialysis. In addition, NAM is well-tolerated and seems not to increase the risk of thrombocytopenia. Thus, NAM can be valuable as "add-on" treatment to combat hyperphosphatemia in patients with kidney failure. However, more research in larger populations is needed to confirm this.