Objective: To identify risk factors for recurrence of tuberculosis. Methods: We studied a cohort of 610 patients with active pulmonary tuberculosis who were enrolled for treatment between 1989 and 1994 and cured using a three-drug treatment regimen of rifampin, isoniazid and pyrazinamide (RHZ). The risk factors studied were age, gender, race, duration of symptoms, lesion cavitation, extent of disease, diabetes mellitus, alcoholism, HIV infection, delayed negative sputum conversion, treatment compliance, and medication doses. In order to detect recurrence, the patients were monitored through the Rio Grande do Sul State Healt Department Information System for 7.7 ± 2.0 years after cure. Data were analyzed using the Student's t-test, the chi-square test or Fisher's exact test, and Cox regression models. Results: There were 26 cases of recurrence (4.3%), which corresponds to 0.55/100 patients-year. The recurrence rate was 5.95 and 0.48/100 patients-year in HIV-positive and HIV-negative patients, respectively (p < 0.0001). In the multivariate analysis, HIV infection [RR = 8.04 (95% CI: 2.35-27.50); p = 0.001] and noncompliance [RR = 6.43 (95% CI: 2.02-20.44); p = 0.002] proved to be independently associated with recurrence of tuberculosis. Conclusions: Recurrence of tuberculosis was more common in HIV-positive patients and in patients who did not comply with the self-administered treatment (RHZ regimen). Patients presenting at least one of these risk factors can benefit from the implementation of a post-treatment surveillance system for early detection of recurrence. An alternative to prevent noncompliance with tuberculosis treatment would be the use of supervised treatment.

Keywords: Tuberculosis; Recurrence; Risk factors.