High-Dose Vitamin D during Tuberculosis Treatment in Mongolia. A Randomized Controlled Trial.

RATIONALE

Existing trials of adjunctive vitamin D in the treatment of pulmonary tuberculosis (PTB) are variously limited by small sample sizes, inadequate dosing regimens, and high baseline vitamin D status among participants. Comprehensive analyses of the effects of genetic variation in the vitamin D pathway on response to vitamin D supplementation are lacking.

OBJECTIVES

To determine the effect of high-dose vitamin D on response to antimicrobial therapy for PTB and to evaluate the influence of single-nucleotide polymorphisms (SNPs) in vitamin D pathway genes on response to adjunctive vitamin D.

METHODS

We conducted a clinical trial in 390 adults with PTB in Ulaanbaatar, Mongolia, who were randomized to receive four biweekly doses of 3.5 mg (140,000 IU) vitamin D (n = 190) or placebo (n = 200) during intensive-phase antituberculosis treatment.

MEASUREMENTS AND MAIN RESULTS

The intervention elevated 8-week serum 25-hydroxyvitamin D concentrations (154.5 nmol/L vs. 15.2 nmol/L in active vs. placebo arms, respectively; 95% confidence interval for difference, 125.9-154.7 nmol/L; P < 0.001) but did not influence time to sputum culture conversion overall (adjusted hazard ratio, 1.09; 95% confidence interval, 0.86-1.36; P = 0.48). Adjunctive vitamin D accelerated sputum culture conversion in patients with one or more minor alleles for SNPs in genes encoding the vitamin D receptor (rs4334089, rs11568820) and 25-hydroxyvitamin D 1α-hydroxylase (CYP27B1: rs4646536) (adjusted hazard ratio ≥ 1.47; P for interaction ≤ 0.02).

CONCLUSIONS

Vitamin D did not influence time to sputum culture conversion in the study population overall. Effects of the intervention were modified by SNPs in VDR and CYP27B1. Clinical trial registered with www.clinicaltrials.gov (NCT01657656).