Vitamin D supplementation flops for TB prevention in children

A 3-year course of weekly oral vitamin D supplementation, while safe and effective at increasing serum 25(OH)D concentrations, does little to reduce the risk of contracting tuberculosis (TB) infection in children, as shown in the results of a phase III study.

The study was conducted in Cape Town, South Africa, and included 1,682 school-aged children who had negative QuantiFERON-TB Gold Plus (QFT-Plus) assay results at baseline. These children were randomly assigned to receive supplementation with 10,000 IU vitamin D3 (n=829) or placebo (n=853) for 3 years. The primary endpoint was a positive end-trial QFT-Plus result.

The mean age of the children was 8.9 years, and 52.4 percent were girls. Most of the children (97.9 percent) were of Xhosa ethnic origin. The mean baseline deseasonalized serum 25(OH)D₃ level was 71.2 nmol/L, and 63.2 percent of the children had levels below 75 nmol/L.

A total of 1,354 children (80.5 percent) had valid end-trial QFT-Plus results and were included in the analysis of the primary outcome. The median follow-up duration was 3.16 years. At the end of the trial, mean serum 25(OH)D₃ levels were higher in the vitamin D group than in the placebo group (104.3 vs 64.7 nmol/L). Significantly more children in the vitamin D group had had serum 25(OH)D₃ concentration ≥75 nmol/L (90.4 percent vs 25.0 percent; p<0.001).

However, the proportion of children with a positive end-trial QFT-Plus result did not significantly differ between the vitamin D and placebo groups (11.4 percent vs 13.0 percent; adjusted odds ratio, 0.86, 95 percent confidence interval, 0.62–1.19; p=0.35).