Tuberculosis incidence rate and risk factors among HIV-infected adults with access to antiretroviral therapy

Objective: The objective of this study is to determine the incidence rate and risk factors of tuberculosis (TB) among HIV-infected adults accessing antiretroviral therapy (ART) in Tanzania. Design: A prospective observational study among HIV-infected adults attending HIV clinics in Dar es Salaam. Methods: We estimated TB incidence rates among HIV-infected patients prior to and after ART initiation. We used Cox proportional hazard regressions to determine the predictors of incident TB among HIV-infected adults enrolled in the HIV care and treatment programme. Results: We assessed 67 686 patients for a median follow-up period of 24 (interquartile range: 8-49) months; 7602 patients were diagnosed with active TB. The TB incidence rate was 7.9 [95% confidence interval (95% CI), 7.6-8.2] per 100 person-years prior to ART initiation, and 4.4 (95% CI, 4.2-4.4) per 100 person-years for patients receiving ART. In multivariate analyses, patients on ART in the first 3 months had a 57% higher risk of TB (hazard ratio: 1.57, 95% CI, 1.47-1.68) than those not on ART, but the risk significantly decreased with increasing duration of ART. Risk factors for incident TB included being male, having low BMI or middle upper arm circumference, lower CD4(+) cell count and advanced WHO disease stage. There was seasonal variation for incident TB, with higher risk observed following the rainy seasons (May, June and November). Conclusion: In TB endemic regions, HIV-infected patients initiating ART, particularly men and those with poor nutritional status, should be closely monitored for active TB at ART initiation. In addition to increasing the access to ART, interventions should be considered to improve nutritional status among HIV-infected patients.