It is not known whether the risk of active tuberculosis disease varies with the length of time that individuals are infected with HIV.Objective:
To study how, independently of CD4 T cell count, the risk of tuberculosis varies with the duration of HIV infection.Methods:
Using Poisson regression analysis, the incidence of and risk factors for tuberculosis were studied in 683 injecting drug users (IDU) with a documented date of HIV seroconversion followed in seven cohorts in six European countries until 1998.Results:
Overall incidence was 11.5/1000 person-years. Adjusted for CD4 T cell count and geographic region, the risk ratio (RR) for tuberculosis (both pulmonary and extrapulmonary), compared with the first 3 years of HIV infection, was 2.8 for years 4 to 6 of HIV infection [95% confidence interval (CI), 1.3–6.3], 1.2 for year 7 to 9 (95% CI, 0.3–4.2) and 4.6 after 9 years (95% CI, 1.4–15.0). The adjusted RR for geographic region was 13.1 (95% CI, 4.3–40.0) for Amsterdam and 15.8 (95% CI, 4.8–52.0) for the Valencian region of Spain compared with all other sites combined.Conclusion:
The risk of tuberculosis is increased relatively early in HIV infection (year 4 to 6) and also later (after year 9) with possibly a relatively silent period between. As expected, IDU in Southern Europe have a substantially higher risk of tuberculosis than IDU in Northern and Central Europe. Amsterdam forms an exception for Northern Europe, with very high incidence rates.