A randomised controlled trial of high-dose isoniazid adjuvant therapy for multidrug-resistant tuberculosis

Abstract

Setting: Tertiary care hospital in Kanpur, India.

Background: The need for a standardised treatment protocol for multidrug-resistant tuberculosis (MDR-TB) in resource-limited countries is being increasingly recognised.

Objective: To assess the effectiveness of high-dose isoniazid (INH) (16-18 mg/kg) adjuvant to second-line therapy in documented cases of MDR-TB.

Design: The present study is a double blind, randomised controlled trial with three treatment arms, high-dose INH, normal-dose INH and placebo, in addition to second-line drugs. Primary outcomes of the study were time to sputum culture conversion and proportion with sputum culture negative 6 months after treatment initiation. Secondary outcomes were radiological improvement at 1 year post treatment and development of toxicity.

Results: After adjustment for potential confounders, subjects who received high-dose INH became sputum-negative 2.38 times (95%CI 1.45-3.91, P = 0.001) more rapidly than those who did not receive it, and had a 2.37 times (95%CI 1.46-3.84, P < 0.001) higher likelihood of being sputum-negative at 6 months. These subjects showed significantly better radiological improvement without an increased risk of INH toxicity.

Conclusion: In low-resource scenarios where a standardised therapeutic protocol is used for MDR-TB, the protocol can be significantly improved by including high-dose INH as an adjuvant.