Tuberculosis recurrence in smear-positive patients cured under DOTS in southern Ethiopia: retrospective cohort study

BACKGROUND Decentralization of DOTS has increased the number of cured smear-positive tuberculosis (TB) patients. However, the rate of recurrence has increased mainly due to HIV infection. Recurrence rate could be taken as an important measure of long-term success of TB treatment. We aimed to find out the rate of recurrence in smear-positive patients cured under DOTS in southern Ethiopia. METHODS We did a retrospective cohort study on cured smear-positive TB patients who were treated from 1998 to 2006. Recurrence of smear-positive TB was used as an outcome measure. Person-years of observation (PYO) were calculated per 100 PYO from the date of cure to date of interview. Kaplan-Meier and Cox-regression methods were used to determine the survival and the hazard ratio (HR). RESULTS 368 cured smear-positive TB patients which were followed for 1463 person-years. Of these, 187 patients (50.8%) were men, 277 patients (75.5%) were married, 157 (44.2%) were illiterate, and 152 patients (41.3%) were farmers. 15 of 368 smear-positive patients had recurrence. The rate of recurrence was 1 per 100 PYO (0.01 per annum). Recurrence was not associated with age, sex, occupation, marital status and level of education. CONCLUSION High recurrence rate occurred among smear-positive patients cured under DOTS. Further studies are required to identify factors contributing to high recurrence rates to improve disease free survival of TB patients after treatment.