Tuberculosis incidence rates during 8 years of follow-up of an antiretroviral treatment cohort in South Africa: comparison with rates in the community

• Published in: PloS one 2012-03, Vol.7 (3), p.e34156-e34156
• Main Authors: Gupta, Ankur, Wood, Robin, Kaplan, Richard, Bekker, Linda-Gail, Lawn, Stephen D
• Format: Article
• Language: English
• Subjects: Acquired immune deficiency syndrome; Adult; AIDS; Analysis; Anti-Retroviral Agents - therapeutic use; Antiretroviral agents; Antiretroviral drugs; Antiretroviral therapy; Biology; CD4 antigen; CD4 Lymphocyte Count; Cell culture; Cohort Studies; Communicable Disease Control - methods; Communities; Female; Follow-Up Studies; Highly active antiretroviral therapy; HIV; HIV Infections - complications; HIV Infections - drug therapy; HIV Infections - epidemiology; HIV Infections - virology; Human immunodeficiency virus; Humans; Incidence; Infectious Disease Medicine - methods; Male; Mass Screening - methods; Medical diagnosis; Medicine; Patients; Recovery; South Africa; Time Factors; Tuberculosis; Tuberculosis - complications; Tuberculosis - epidemiology; Tutu, Desmond
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0034156

Although antiretroviral therapy (ART) is known to be associated with time-dependent reductions in tuberculosis (TB) incidence, the long-term impact of ART on incidence remains imprecisely defined due to limited duration of follow-up and incomplete CD4 cell count recovery in existing studies. We determined TB incidence in a South African ART cohort with up to 8 years of follow-up and stratified rates according to CD4 cell count recovery. We compared these rates with those of HIV-uninfected individuals living in the same community. Prospectively collected clinical data on patients receiving ART in a community-based cohort in Cape Town were analysed. 1544 patients with a median follow-up of 5.0 years (IQR 2.4-5.8) were included in the analysis. 484 episodes of incident TB (73.6% culture-confirmed) were diagnosed in 424 patients during 6506 person-years (PYs) of follow-up. The TB incidence rate during the first year of ART was 12.4 (95% CI 10.8-14.4) cases/100PYs and decreased to 4.92 (95% CI 3.64-8.62) cases/100PYs between 5 and 8 years of ART. During person-time accrued within CD4 cell strata 0-100, 101-200, 201-300, 301-400, 401-500, 501-700 and ≥700 cells/µL, TB incidence rates (95% CI) were 25.5 (21.6-30.3), 11.2 (9.4-13.5), 7.9 (6.4-9.7), 5.0 (3.9-6.6), 5.1 (3.8-6.8), 4.1 (3.1-5.4) and 2.7 (1.7-4.5) cases/100PYs, respectively. Overall, 75% (95% CI 70.9-78.8) of TB episodes were recurrent cases. Updated CD4 cell count and viral load measurements were independently associated with long-term TB risk. TB rates during person-time accrued in the highest CD4 cell count stratum (>700 cells/µL) were 4.4-fold higher that the rate in HIV uninfected individuals living in the same community (2.7 versus 0.62 cases/100PYs; 95%CI 0.58-0.65). TB rates during long-term ART remained substantially greater than rates in the local HIV uninfected populations regardless of duration of ART or attainment of CD4 cell counts exceeding 700 cells/µL.