Background: We aimed to estimate the effect of anti-retroviral therapy (ART) on incident tuberculosis (TB) in a cohort of HIV-infected children.
Methods: We analysed data from ART-naïve, TB disease-free children enrolled between December 2004 and April 2008 into an HIV care program in Kinshasa, Democratic Republic of Congo. To estimate the effect of ART on TB incidence while accounting for time-dependent confounders affected by exposure, a Cox proportional hazards marginal structural model was used.
Results: 364 children contributed 596.0 person-years of follow-up. At baseline, the median age was 6.9 years; 163 (44.8%) were in HIV clinical stage 3 or 4. During follow-up, 242 (66.5%) children initiated ART and 81 (22.3%) developed TB. At TB diagnosis, 41 (50.6%) were receiving ART. The TB incidence rate in those receiving ART was 10.2 per 100 person-years [95% confidence interval (CI) 7.4-13.9] compared with 20.4 per 100 person-years (95% CI 14.6-27.8) in those receiving only primary HIV care. TB incidence decreased with time on ART, from 18.9 per 100 person-years in the first 6 months to 5.3 per 100 person-years after 12 months of ART. The model-estimated TB hazard ratio for ART was 0.51 (95% CI 0.27-0.94).
Conclusions: For HIV-infected children in TB-endemic areas, ART reduces the hazard of developing TB by 50%.