[The cost effectiveness of the study of the familial contacts of tuberculosis patients coinfected with the human immunodeficiency virus].

The investigation of contacts of patients with tuberculosis is a highly cost-effective measure to detect new cases of disease and infected individuals; nevertheless, its efficacy has not been contrasted with persons living with patients with tuberculosis (TB) coinfected with HIV. A total of 152 family contacts were studied corresponding to 84 HIV-positive tuberculosis patients. As a control group, 516 persons living with HIV-negative TB patients were included. Contacts were classified according to the bacteriologic status of the index case (IC): group I, contacts of patients with negative bacterioscopy and positive culture of respiratory specimens; group II, contacts of patients with negative bacterioscopy and positive culture of respiratory specimens, and group III, contacts of pulmonary and/or extrapulmonary TB patients with negative bacterioscopy and culture. Among IC coinfected with HIV there was a higher percentage of extrapulmonary clinical forms and therefore a lower proportion of bacillary forms, which accounted for a lower rate of infection among contacts of HIV-positive patients than among contacts of HIV-negative patients (20.4% vs 48.8%; OR: 3.7; 95% CI: 2.4-5.9). After controlling for bacteriologic status of the IC, differences remained when bacillary (group I) of HIV-coinfected patients were compared with those of patients not coinfected with HIV (35.9% vs 52.3%; OR: 2.1%; 95% CI: 1.2-5.9). Overall, 28 new TB cases were detected (4.2% of the total of studied persons living with TB patients) with no differences among contacts of both groups. The lower rate of infections among persons living with HIV-positive patients might be due not only to a lower number of pulmonary forms in HIV-coinfected IC and therefore less bacillary forms but also to a lower degree of crowding and a higher protection against exposure to their contacts.