Objective: To estimate incidence rates and risk factors for tuberculosis (TB) in human immunodeficiency virus seroprevalent subjects.
Methods: Multicentre, hospital-based cohort study of patients presenting to 10 Spanish hospitals from 1 January 1997 to 31 December 2003. Poisson regression was used and highly active antiretroviral treatment (HAART) was modelled as a time-dependent covariate.
Results: A total of 4268 patients were followed for a median of 3.8 years; 221 TB cases were diagnosed over 16 464 person-years (py). TB rates were higher in HAART-naïve subjects (1.56 per 100 py, 95%CI 1.36-1.79) than those on HAART (0.5/100 py, 95%CI 0.31-0.80). Among HAART-naïves, TB risk factors were: being male, being an injecting drug user (IDU) (RR 2.01, 95%CI 1.28-3.16), having low CD4 counts (P < 0.001) and high viral loads (P < 0.001). HAART was protective (RR 0.26, 95%CI 0.16-0.40) and reductions in TB rates were observed in the last calendar period (RR 0.74, 95%CI 0.55-1.00). For patients on HAART, no differences were observed by category of transmission. Low CD4 counts at entry were associated with higher TB rates (P < 0.001).
Conclusions: HAART was associated with lower TB rates, and TB risk factors differed according to whether or not patients had received HAART. To further reduce TB rates, additional strategies are needed, such as timely access and adherence to HAART, especially in IDUs.