Five-Year Assessment of Time of Sputum Smears Conversion and Outcome and Risk Factors of Tuberculosis Patients in Central Iran

Objective. To evaluate risk factors which influence sputum smear conversion, outcome, and trends of conversion of sputum smear during 5 years and compare outcomes in patients with different regimens. Methods. In a retrospective cohort study, all patients with sputum smear positive tuberculosis were evaluated for comorbidities and demographic, microbiological, and therapeutic data and outcome. Smear examinations were performed at the beginning, at 2 months for CAT I, at 3 months for CAT II, at the end of second month of maintenance phase, and at the end of treatment. Results. This study enrolled 211 sputum smear positive patients, but 189 patients who completed the intensive phase of treatment were evaluated. Sputum smear of 158 patients converted at the end of intensive phase (83.6). Univariate analysis indicated that the risk of a persistent positive smear at the end of intensive phase was greater in diabetic patients ((odds 4.038, 95% CI 1.123-14.516) P = 0.033), and also a 3+bacillary load had risk of 2.933-fold ((95% CI 1.278-6.732) P = 0.011). Overall rate of unfavorable outcome was 20.9%. Factors associated with unfavorable outcome were age (P value 0.000), male gender (P value 0.027), diabetes (P value 0.000), and delayed conversion of sputum at the end of intensive phase (P value 0.000). Outcome for different regimens was not different significantly. Two specimens were isoniazid resistant. Conclusions. We suggest supervised treatment and care for diabetic patients and those with higher bacillary load. Paying attention to early diagnosis of tuberculosis in the elderly to reduce poor outcome and further measures to prevent transfer-out could improve the success rate.