Predictors of Smear non-conversion among Adult Patients Newly Treated for Bacteriologically Confirmed Pulmonary Tuberculosis at Shashemenne Referral Hospital – A Retrospective Cohort Study

Abstract

Introduction: Sputum smear non-conversion at the second month of tuberculosis treatment is a major predictor of patient infectivity and treatment failure. We aimed to identify the factors associated with smear non-conversion in patients newly treated for bacteriologically confirmed pulmonary tuberculosis. Method and Material: A retrospective cohort study was conducted on adult patients newly treated for bacteriologically confirmed pulmonary tuberculosis enrolled from 2002 to 2011 at Shashemenne Referral Hospital. Data on socio-demographic factors, comorbidities, drug-related factors, substance use, and baseline bacilli grading were extracted from TB registered and patient cards by using a structured tool. Two nurses and one supervisor collected the data after being trained. Finally, a binary logistic regression was employed for analysis to determine the predictor of the smear non-conversion with a 95% confidence interval and 0.05 significance level. Result: Of the 521 who had included in the analysis, 10.7% (56) overall smear non conversion rate was found at their 2nd months of treatment. The mean age was 38.9 ± 13.2 SD, and 52.9% (276) were male sex. Being BMI < 18.5 kg/m2 [AOR = 2.15, (1.08, 4.27)], having history of smoking [AOR = 2.53, (1.13, 5.64)], and grade 3+ smear bacilli density [AOR= 2.57, (1.19, 5.58)] were found to be an independent predictor of smear non-conversion at 2nd months of treatment. Conclusion: Pulmonary tuberculosis patients with the above independent predictors were the major reservoirs for TB transmission both before treatment and after treatment. The longer smear conversion period in those patients could further prolong the exposure period for the contacts. Hence, comprehensive infection prevention measures should be applied for patients with a history of smoking, undernutrition, and grade 3+ pretreatment bacilli density