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.

Objective: To describe the differences in the clinical and radiological presentation of tuberculosis in the presence or absence of HIV infection. Methods: A sample of 231 consecutive adults with active pulmonary tuberculosis admitted to a tuberculosis hospital were studied, assessing HIV infection, AIDS, and associated factors, as well as re-evaluating chest X-rays. Results: There were 113 HIV-positive patients (49%) Comparing the 113 HIV-positive patients (49%) to the 118 HIV-negative patients (51%), the former presented a higher frequency of atypical pulmonary tuberculosis (pulmonary lesions accompanied by intrathoracic lymph node enlargement), hematogenous tuberculosis, and pulmonary tuberculosis accompanied by superficial lymph node enlargement, as well as presenting less pulmonary cavitation. The same was found when HIV-positive patients with AIDS were compared to those without AIDS. There were no differences between the HIV-positive patients without AIDS and the HIV-negative patients. Median CD4 counts were lower in HIV-positive patients with intrathoracic lymph node enlargement and pulmonary lesions than in the HIV-positive patients with pulmonary lesions only (47 vs. 266 cells/mm3; p < 0.0001), in HIV-positive patients with AIDS than in those without AIDS (136 vs. 398 cells/mm3; p < 0.0001) and in patients with atypical pulmonary tuberculosis than in those with other forms of tuberculosis (31 vs. 258 cells/mm3; p < 0.01). Conclusion: Atypical forms and disseminated disease predominate among patients with advanced immunosuppression. In regions where TB prevalence is high, the presence of atypical pulmonary tuberculosis or pulmonary tuberculosis accompanied by superficial lymph node enlargement should be considered an AIDS-defining condition.

Keywords: Tuberculosis, pulmonary; HIV infections; Radiography, thoracic.