Response to treatment is monitored on the basis of monthly sputum smear microscopy and culture (ideally at the same frequency). This is similar to the schedule used in patients on longer MDR-TB regimens. While awaiting updated definitions, the treatment outcome definitions and reporting framework for patients on the shorter MDR-TB regimen are the same as those for patients on longer MDR-TB regimens (26).
Treatment must be administered under closely monitored conditions to enable optimal drug effectiveness and safety, and to monitor for the acquisition of emerging drug resistance, should it arise. Given that the BPaL regimen is a new and shorter regimen that includes a novel medicine and is being implemented under operational research conditions, it is also important to follow up patients after the completion of treatment, to ensure that there is no relapse. In the Nix-TB study, monitoring after completion of treatment was carried out monthly for months 1–3, then at 3-monthly intervals thereafter. Follow-up after treatment completion was for a total of 24 months; however, at the time of data analysis, about half of the patients had been followed up for this period. The analysis of the Nix-TB study data indicated that treatment failure or recurrence occurred in three patients (2.8% of patients overall), taking into account the period of post-treatment completion follow-up.