Incidence of Tuberculosis amongst HIV positive individuals initiating antiretroviral treatment at higher CD4 counts in the HPTN 071 (PopART) trial in South Africa.

Abstract

INTRODUCTION: Antiretroviral treatment (ART) guidelines recommend lifelong ART for all HIV positive individuals. This study evaluated TB incidence on ART in a cohort of HIV positive individuals starting ART regardless of CD4 count in a programmatic setting at three clinics included in the HPTN 071 (PopART) trial in South Africa. METHODS: A retrospective cohort analysis of HIV-positive individuals aged ≥18 years starting ART, between January 2014 and November 2015, was conducted. Follow up was continued until 30 May 2016 or censored on the date of i) incident TB ii) loss to follow up from HIV care or death or iii) elective transfer out; whichever occurred first. RESULTS: The study included 2423 individuals. Median baseline CD4 count was 328 cells/µL (IQR 195-468), TB incidence rate was 4.41/100 PY (95% CI 3.62-5.39). The adjusted hazard ratio of incident TB was 0.27 (95% CI 0.12 - 0.62) when comparing individuals with baseline CD4 > 500cells/µL and ≤ 500cells/µL. Amongst individuals with baseline CD4 count > 500cells/µL there were no incident TB cases in the first three months of follow up. Adjusted hazard of incident TB was also higher amongst men (aHR 2.16; 95% CI: 1.41 - 3.30). CONCLUSION: TB incidence after ART initiation was significantly lower amongst individuals starting ART at CD4 counts above 500cells/µL. Scale up of ART, regardless of CD4 count, has the potential to significantly reduce TB incidence amongst HIV-positive individuals. However, this needs to be combined with strengthening of other TB prevention strategies that target both HIV positive and HIV negative individuals.