The incidence of recurrence of tuberculosis and its related factors in smear-positive pulmonary tuberculosis patients in Iran: A retrospective cohort study

Background and Aim: Studying the recurrence of smear-positive pulmonary tuberculosis (TB) is a convenient way to evaluate the effectiveness of TB control programs and identify vulnerable patients. In the present study, the rate of recurrence of TB and its predictors were determined in Iran. Materials and Methods: This study was a retrospective cohort. Eligible people were patients with smear-positive TB who were diagnosed from 2002 to 2011. The end of the follow-up time was December 2013. The number of people who entered the cohort was 1,271 subjects. In order to determine the predictors of recurrence, multivariate logistic regression was used. Analysis was done using SPSS 20. Results: The recurrence incidence was 8.3% and in 85.9% of these patients, it occurred in the time interval of 1-5 years after successful treatment. The recurrence rate was not significantly related to gender, age group, and diabetes. But it was significantly higher in patients whose sputum smear grading before treatment was 2 + or more, patients with positive sputum smear at the end of the second month of the treatment, patients who had completed treatment, and patients who were smokers (P < 0.05). Conclusions: Our study showed that a considerable percentage of smear-positive pulmonary TB patients experience recurrence and that some patients are at a higher risk of recurrence.