Effect of Antiretroviral Therapy on Treatment Outcomes in a Prospective Study of Extensively Drug-Resistant Tuberculosis (XDR-TB) HIV Coinfection Treatment in KwaZulu-Natal, South Africa

Abstract

Background: Extensively drug-resistant tuberculosis (XDR-TB)/HIV coinfection has been associated with high mortality and poor TB outcomes. We performed a prospective study to comprehensively characterize a cohort of patients with XDR-TB.

Methods: Adult patients with XDR-TB were enrolled at treatment initiation at a TB referral hospital in KwaZulu-Natal Province, South Africa, and followed through the end of treatment. Clinical data, questionnaires, adherence data, and sputum were collected monthly. Whole genome sequencing was performed on baseline Mycobacterium tuberculosis (MTB) isolates. Treatment outcomes were defined using standard definitions.

Results: One hundred five patients with XDR-TB (76.1% HIV-infected) were enrolled from August 2009 to July 2011. Among HIV-coinfected patients, 82.5% were on antiretroviral therapy initially and 93.8% cumulatively over the study period. At 24 months, 31.4% had a successful outcome and 68.6% had an unsuccessful outcome with 41% mortality. Antiretroviral therapy was associated with improved mortality in HIV-coinfected patients (P = 0.05), as was TB culture conversion (P < 0.0001). On whole genome sequencing, most strains were LAM4/KZN lineage (68%), with few single nucleotide polymorphism differences.

Conclusions: Despite improved HIV care, treatment outcomes and mortality were only modestly improved compared with previous South African XDR-TB/HIV treatment cohorts. Of note, this study was completed before the introduction of new antimycobacterial agents (eg, bedaquiline and delamanid). As new TB drugs and regimens become available, it is important to monitor treatment to ensure that benefits seen in clinical trials are reproduced in high-burden, low-resource settings.

Figures

Figure 1.

Kaplan-Meier survival estimates (A) Probability of survival stratified by HIV status at XDR-TB treatment initiation (B) Probability of survival stratified by ART status (C) Probability of survival stratified by culture conversion

Figure 2.

Dendrogram of the subset of XDR-TB isolates sequenced using whole genome sequencing. The majority of strains (35/50 68%) were KZN LAM4 with an average of 10.71 SNP differences between these strains (n = 50).