Factors influencing treatment outcomes in patients with isoniazid-resistant pulmonary TB

INTRODUCTION: Patients with isoniazid (H, INH) resistant pulmonary TB but undetected rifampicin (R, RIF) resistance are treated with a 6-month regimen of levofloxacin-RIF-ethambutol-pyrazinamide (6LvxREZ) under India´s National TB Elimination Programme (NTEP).

OBJECTIVE: To describe the profile of and treatment outcomes in patients with pulmonary INH-resistant (INH^R) TB initiated on TB treatment, and identify factors associated with unfavourable treatment outcomes (died, failed, treatment changed, lost to follow-up).

METHODS: This was a retrospective analysis of NTEP database (Ni-kshay) on pulmonary INH^R TB patients initiated on treatment with “H mono/poly regimen” (6LvxREZ) between July 2019 and June 2020 with documented treatment outcomes. Proportions with 95% confidence interval (CI) was calculated and logistic regression analysis was performed.

RESULTS: Of the 11,519 patients with pulmonary INH^R TB, 9,440 (82%) had treatment success (55.1% cured, 26.9% treatment completed). Unfavourable treatment outcome was observed in 1,901 (16.5%). Male sex, tobacco and alcohol use, HIV reactive status were associated with unfavourable treatment outcome. Patients with katG mutations and resistance to fluoroquinolones were likely to have poor treatment outcomes.

CONCLUSION: A levofloxacin-based regimen offers a treatment success rate of 82% in patients with pulmonary INH^R TB. Sex-specific strategies, interventions to address smoking and alcohol use, focus on HIV-reactive patients and optimising treatment regimens based on drug susceptibility should be considered for improving treatment outcomes.