Treatment outcomes among patients with isoniazid mono-resistant tuberculosis in Mumbai, India: A retrospective cohort study

BACKGROUND

Tuberculosis (TB) remains a significant cause of mortality globally, with India accounting for 27% of the estimated number of people with TB. Multidrug-resistant TB (MDR-TB) and isoniazid (INH) resistance pose additional challenges to effective treatment. We aimed to describe treatment outcomes of INH mono-resistant TB patients under programmatic conditions in Mumbai, India.

METHODS

This retrospective cohort study was conducted at Shatabdi Hospital in Mumbai between 2019-2021.We described the clinical and demographic characteristics, treatment outcomes, and risk factors for unfavourable outcomes among patients with INH mono-resistant TB treated with rifampicin, ethambutol, pyrazinamide, and levofloxacin (LfxREZ) for a duration of 6 months.

RESULTS

Among 3105 patients with drug-resistant TB initiated on treatment, 217 (7 %) had INH mono-resistant TB. Of these, 54 % (117/217) were female, with a median age of 26 years (interquartile range: 20-40). The majority (88 %; 191/217) presented with pulmonary TB, and most (87 %; 188/217) had favourable treatment outcomes, including treatment completion (52 %; 112/217) and cure (35 %; 76/217). Unfavourable outcomes, including treatment failure (2.3 %; 5/217), loss to follow-up (9.2 %; 20/217), or death (1.8 %; 4/217), were observed in 13 % (29/217) of patients. A total of ten (5 %) patients experienced at least one non-severe adverse drug reaction. Factors associated with unfavourable outcomes included severe thinness (p = 0.019) and male gender (p = 0.012).

CONCLUSION

Treating INH mono-resistant patients with LfxREZ resulted in satisfactory outcomes and low toxicity. It is important to rule out drug resistance to INH while determining the treatment regimen.