Abstract
OBJECTIVE: To determine tuberculosis (TB) incidence rates and risk factors among individuals receiving antiretroviral treatment (ART). DESIGN: Observational cohort in Johannesburg, South Africa. METHODS: Incident TB was classified as early (less than 6 months of ART) or late (greater than 6 months of ART) incident TB. CD4 cell counts, viral load, body mass index, and hemoglobin were measured 6-monthly. Hazard ratios for factors associated with early and late incident TB were assessed using Cox proportional hazards regression. RESULTS: During 13,416 person-years of follow-up, 501 TB cases occurred among 7536 individuals, corresponding to a 10% risk in the first 4 years of ART and an overall incidence rate of 4.2 cases/100 person-years. The highest incidence rate (21.7 per 100 person-years) was observed in the first 3 months of ART among people with CD4 count below 50 cells/mm3. Low baseline CD4 count, anemia, and low body mass index were the strongest risk factors for early incident TB. Low updated CD4 count, low updated body mass index, anemia, and high viral load on ART were strong risk factors for late incident TB. CONCLUSIONS: Severity of HIV disease and unfavorable response to ART are associated with early and late incident TB, respectively. Early ART initiation and intensified TB screening at ART initiation are crucial to reduce incident TB.