Outcomes and Adverse Events of WHO Shorter Regimen in the Treatment of Multi-Drug Resistant Tuberculosis in Bhutan: A Longitudinal Study

Background and aims Bhutan first introduced the Shorter Regimen, consisting of a combination of Amikacin, Clofazamine, Ethionamide, Ethambutol, high dose Isoniazid, Moxifloxacin and Pyrazinamide, for the treatment of rifampicin or multidrug resistant tuberculosis (RR/MDR-TB) in 2018. This study describes the outcome, time to sputum conversion and adverse events of treatment among MDR-TB patients treated with the Shorter Regimen in Bhutan. Methods This was a longitudinal study among patients with RR/MDR-TB who were treated with the Shorten Regimen between 2018 and 2020. Throughout the treatment period, sputum smear, culture, and blood investigations were monitored. Results There were 52 patients who received the shorter regimen for MDR-TB. Forty-seven patients (90%) had pulmonary TB (PTB) and five (10%) had extra-pulmonary TB (EPTB). Forty-one patients (79%) had confirmed MDR-TB and 11 (21%) had RR-TB. MDR-TB was detected in new cases in 35 patients (69%), while 11 (22%) were cases of TB relapse and five (10%) were cases of treatment failure. There were 40 patients (86%) who achieved sputum smear conversion by the end of 4 months while all patients became culture negative by the end of 3 months. All patients achieved culture conversion by the end of 3 months. The treatment success rate was 94% and there were no deaths. The common side effects were nausea, vomiting, arthralgia, dizziness, sleep disturbances, depressed mood and skin rash. QTc prolongations were observed in six patients, for which five patients needed dose modification of Moxifloxacin. Five patients had hepatitis, and two needed dose modification. Two patients were switched to the longer regimen due to amikacin-induced profound hearing loss and nephrotoxicity. Conclusions The treatment success rate of MDR-TB was high, with high sputum and culture conversion rates. Adequate monitoring of side effects is important in providing timely intervention.