Association between tuberculosis and HIV disease progression in a high tuberculosis prevalence area.

SETTING: Adult human immunodeficiency virus (HIV) clinics affiliated to the University of Cape Town, South Africa.
OBJECTIVE: To assess the impact of tuberculosis on HIV-1 disease progression in an area with high tuberculosis prevalence and minimal antiretroviral therapy use.
DESIGN: Prospective patient cohort study.
METHODS: Age, race, risk status, CD4+ T-lymphocyte count, history of AIDS, prophylactic co-trimoxazole and antiretroviral therapy were controlled for in a time-dependent Cox proportional hazards regression model.
RESULTS: Tuberculosis fulfilling the case definition developed in 158/609 patients in the 5-year observation period. Tuberculosis was associated with an increased risk of AIDS (adjusted risk ratio [RR] = 1.60, 95% confidence interval [CI] 1.08-2.41; P = 0.02) and death (adjusted RR = 2.16, 95% CI 1.29-3.59; P = 0.003). In a stratified analysis, the increased mortality associated with tuberculosis was observed only in patients with CD4+ T-lymphocyte count > 200 cells/microliter and in those without AIDS at baseline.
CONCLUSION: The onset of tuberculosis in HIV-infected patients is associated with an increased risk of AIDS and death. Although a causal link cannot be established in an observational study, our findings support the view that prolonged immune activation induced by tuberculosis leads to prolonged increased HIV replication and consequent accelerated disease progression.