Objective: To describe the outcomes of retreatment in tuberculosis patients receiving the regimen known, in Brazil, as regimen 3 (streptomycin, ethambutol, ethionamide, and pyrazinamide for 3 months + ethambutol and ethionamide for 9 months) after treatment failure with the basic regimen (rifampin, isoniazid, and pyrazinamide for 2 months + rifampin and isoniazid for 4 months). Methods: A descriptive, uncontrolled, historical cohort study involving adult tuberculosis patients treated with regimen 3. We evaluated adverse drug effects, recurrence, treatment outcomes, and associated factors. Results: The study included 229 patients. The overall cure rate was 62%. For the patients who used the medications regularly and those who did not, the cure rate was 88% and 31%, respectively. Adverse events occurred in 95 patients (41.5%), and most of those events were related to the gastrointestinal tract. In the five-year follow-up period, relapse occurred in 17 cases (12.0%). Conclusions: Overall, the outcomes of treatment with regimen 3 were unsatisfactory, in part because this regimen was administered to a selected population of patients at high risk for noncompliance with treatment, as well as because it presents high rates of adverse effects, especially those related to the gastrointestinal tract, which might be caused by ethionamide. However, for those who took the medications regularly, the cure rate was satisfactory. The recurrence rate was higher than that recommended in international consensus guidelines, which might be attributable to the short (12-month) treatment period. We believe that regimen 3, extended to 18 months, represents an option for patients with proven treatment compliance.

Keywords: Tuberculosis, pulmonary/therapy; Treatment outcome; Retreatment.

Aim: To evaluate the performance of an SHM scheme (streptomycin, isoniazid, and ethambutol) in an outpatient clinic routine treatment for tuberculosis. Method: Seventy-eight patients with tuberculosis whose prior treatment with the RHZ scheme (six months of rifampicin, isoniazid, and pyrazinamide) had to be discontinued due to adverse effects, or who could not receive the RHZ scheme due to high risk for liver toxicity, were treated in the outpatient clinic with the 12 month SHM scheme from 1986 to 1994, in the city of Porto Alegre, Rio Grande do Sul, Brazil. Results: Three patients (3.8%) required a scheme change due to toxicity. In the remaining 75 patients, 58 (77.3%) were cured, eight (10.7%) withdrew, five (6.7%) presented failure, and four (5.3%) died. Theoretical cure rate, which is the percent of cure of patients who regularly followed the treatment, was 95.3%. Adverse reactions were seen in 32 patients (41%), the most frequent being vestibular damage in 18 patients (23.1%). Results were compared to those obtained in the same outpatient clinic with the 12 month RHM scheme (rifampicin, isoniazid, and ethambutol), and with the six month RHZ scheme. Conclusion: The SHM scheme may be recommended as an alternative for the treatment of tuberculosis whenever the RHZ scheme cannot be indicated.