The impact of M. tuberculosis infection on subsequent disseminated MAC disease in KV-infected persons

Introduction: Recent reports suggest that active TB protects against subsequent disseminated MAC (DMAC) disease in HIV-infected persons. It has been suggested that injection drug use and nonwhite race may also protect against DMAC. Methods: We performed an observational cohort study among the 1) AIDS Linked to the Intravenous Experience (ALIVE) cohort of injection drug users and the 2) Johns Hopkins Hospital Adult HIV Clinic cohort to determine the relative risk of DMAC among HIV-infected persons with a history of latent or active TB infection. Results: There were 1,186 HIV-infected persons with CD4 < 100 during the study period of 1988-1996. The cohort was 80% African-American (945 pts), 79% male (937 pts), and 58% injection drug users (IDU) (676 pts). Twenty percent (234 pts) had received rifabutin. There were 71 patients with latent M tuberculosis infection (+PPD without active TB), 31 cases of active TB, and 209 cases of DMAC. Among persons with a history of active TB compared to persons without TB, the relative risk (RR) of DMAC was 1.72 (p=0.09). Among persons with latent M. tuberculosis infection compared to PPD - persons, the RR of DMAC was 0.96 (p=0.86). The RR of DMAC among IDUs was 0.98 (p=0.84); the RR among African-Americans was 1.08 (p=0.64). Results did not vary significantly when stratified according to rifabutin use. Conclusions: Prior infection with M. tuberculosis, IDU, and nonwhite race did not protect against DMAC in this urban cohort of HIV-infected patients.