Treatment outcomes of multi drug resistant and rifampicin resistant Tuberculosis in Zimbabwe: A cohort analysis of patients initiated on treatment during 2010 to 2015

Abstract

Background: Zimbabwe is one of the thirty countries globally with a high burden of multidrug-resistant tuberculosis (TB) or rifampicin-resistant TB (MDR/RR-TB). Since 2010, patients diagnosed with MDR/RR-TB are being treated with 20-24 months of standardized second-line drugs (SLDs). The profile, management and factors associated with unfavourable treatment outcomes of MDR/RR TB have not been systematically evaluated in Zimbabwe.

Objective: To assess treatment outcomes and factors associated with unfavourable outcomes among MDR/RR-TB patients registered and treated under the National Tuberculosis Programme in all the district hospitals and urban healthcare facilities in Zimbabwe between January 2010 and December 2015.

Methods: A cohort study using routinely collected programme data. The 'death', 'loss to follow-up' (LTFU), 'failure' and 'not evaluated' were considered as "unfavourable outcome". A generalized linear model with a log-link and binomial distribution or a Poisson distribution with robust error variances were used to assess factors associated with "unfavourable outcome". The unadjusted and adjusted relative risks were calculated as a measure of association. A 𝑝value< 0.05 was considered statistically significant.

Results: Of the 473 patients in the study, the median age was 34 years [interquartile range, 29-42] and 230 (49%) were males. There were 352 (74%) patients co-infected with HIV, of whom 321 (91%) were on antiretroviral therapy (ART). Severe adverse events (SAEs) were recorded in 118 (25%) patients; mostly hearing impairments (70%) and psychosis (11%). Overall, 184 (39%) patients had 'unfavourable' treatment outcomes [125 (26%) were deaths, 39 (8%) were lost to follow-up, 4 (<1%) were failures and 16 (3%) not evaluated]. Being co-infected with HIV but not on ART [adjusted relative risk (aRR) = 2.60; 95% CI: 1.33-5.09] was independently associated with unfavourable treatment outcomes.

Conclusion: The high unfavourable treatment outcomes among MDR/RR-TB patients on standardized SLDs were coupled with a high occurrence of SAEs in this predominantly HIV co-infected cohort. Switching to individualized all oral shorter treatment regimens should be considered to limit SAEs and improve treatment outcomes. Improving the ART uptake and timeliness of ART initiation can reduce unfavourable outcomes.

Fig 1. Treatment outcomes among MDR/RR TB patients registered in Zimbabwe between 2010 and 2015, stratified by year of treatment commencement.