Objective: To determine the relationship between Mycobacterium tuberculosis infection and disease and subsequent disseminated M. avium complex (MAC) disease in HIV-infected persons.
Design: A prospective observational cohort study.
Setting: The AIDS Linked to the Intravenous Experience (ALIVE) cohort of injecting drug users and the Johns Hopkins Hospital Adult HIV Clinic (JHHAHC).
Participants: HIV-infected persons aged > 18 years with CD4 lymphocytes < 100 x 10(6)/l were followed between July 1989 and 31 October 1996. There were 182 persons in the ALIVE cohort and 1129 persons in JHHAHC who met these criteria.
Main outcome measure: The relative risk of disseminated MAC was determined according to a history of prior opportunistic infection, MAC prophylaxis, antiretroviral therapy, M. tuberculosis infection or disease, race, sex, and injecting drug use.
Results: Amongst the 30 patients with active tuberculosis, eight developed disseminated MAC, compared with 208 cases of disseminated MAC amongst 1148 patients without prior M. tuberculosis infection or disease [relative risk (RR), 1.5; 95% confidence interval (CI), 0.8-2.7; P=0.2]. Amongst the 10 patients with extrapulmonary tuberculosis, five developed disseminated MAC (RR, 2.8; 95% CI, 1.5-5.2; P=0.02). Injecting drug use was associated with a decreased risk of disseminated MAC (RR, 0.7; 95% CI, 0.6-0.9; P=0.007). In a logistic regression analysis, disseminated MAC was significantly associated with extrapulmonary tuberculosis and other opportunistic disease, whereas antibiotic prophylaxis and injecting drug use were protective.
Conclusions: A history of M. tuberculosis infection or disease was not associated with protection against subsequent disseminated MAC disease in HIV-infected persons. However, persons with extrapulmonary tuberculosis were at increased risk for disseminated MAC, particularly at low CD4 cell levels.