Risk factors for tuberculosis in patients with AIDS in London: a case-control study

OBJECTIVE: To identify risk factors for the acquired immune-deficiency synd rome (AIDS) associated with tuberculosis, in patients with AIDS attending 1 1 of the largest human immunodeficiency virus (HIV)/AIDS Units in London. DESIGN: Case-control study nested in a retrospective cohort of 2043 HIV-1 p ositive patients. Cases were defined as patients with a definitive diagnosi s of tuberculosis, and controls as patients with AIDS and without tuberculo sis during follow-up. RESULTS: Of 627 patients diagnosed with AIDS, 121 had a definitive diagnosi s of tuberculosis, Significant risk factors for tuberculosis in the univari ate analysis were sex, ethnicity, age, HIV exposure category and hospital a ttended, and in the multiple regression analysis ethnicity, age and hospita l attended. African ethnicity was the strongest risk factor for tuberculosi s (adjusted odds ratio [AOR] 5.9, 95% confidence interval 3.4-10.2). The ri sk of tuberculosis was higher in the younger age groups (test for trend P < 0.001). The hospital-associated risk of tuberculosis was more heterogeneou s in the non-African group, and non-Africans attending Hospital 1 had an in creased risk of tuberculosis which was statistically significant. CONCLUSIONS: The risk factors for AIDS-associated tuberculosis in London ar e sub-Saharan African origin, younger age group, and, among the non-African s only, attending one hospital in east London. Different transmission patte rns and mechanisms for the development of tuberculosis may operate in diffe rent settings depending on the background risk of tuberculous infection. Sc reening for tuberculosis infection and disease among HIV-positive individua ls in London is important for the provision of preventive or curative thera py, and prophylaxis policies need to be designed in accordance with the tra nsmission patterns and mechanisms of disease.