Treatment Outcomes of Isoniazid-Resistant (Rifampicin Susceptible) Tuberculosis Patients in Uzbekistan, 2017-2018.

Tuberculosis patients "resistant to isoniazid and susceptible to rifampicin (Hr-TB)" remain neglected, despite a high burden and poor outcomes. The World Health Organization (WHO) recommends a 6 month regimen consisting of levofloxacin, rifampicin, ethambutol, and pyrazinamide (LRZE) to treat Hr-TB. In contrast, Uzbekistan uses a 9 month regimen (LRZE plus a second-line injectable in the first 3 months). We aimed to assess the treatment outcomes of this novel regimen among Hr-TB patients treated in two regions of Uzbekistan (Fergana and Bukhara) in 2017-2018. We conducted a cohort study involving secondary analysis of routine surveillance data. Of 132 Hr-TB patients, 105 (80%) were successfully treated. Death was the predominant unsuccessful outcome (13, 10%) followed by "treatment failure" (10, 8%) and "lost to follow-up" (4, 2%). High treatment success is an indicator of the potential effectiveness of the novel regimen and adds to the limited global evidence on this issue. However, the sample size was small and there was no comparison group. Since the study was conducted in two regions of Uzbekistan only, the findings have limited generalizability. We recommend future research using an adequate sample size and an appropriate study design (randomized controlled trial or prospective cohort with a control group receiving the WHO-recommended regimen).