Journal of Knowledge & Health1735-577X14120190618Investigation of the Factors Affecting Duration of Sputum Smear Negative in Smear Positive Pulmonary Tuberculosis Patients Two Months after Treatment222710.22100/jkh.v14i1.2135FAHosseinORCID:0000-0003-2357-590XTireh. firstname.lastname@example.orgParastooORCID:0000-0001-7147-9539GolpourMonavarORCID:0000-0003-2029-6577Afzalaghaee201901022019052720190521Introduction: Pulmonary tuberculosis is one of the most common infectious diseases and second leading cause of death among infectious diseases. Sputum smear negative at the end of the second month of treatment is considered as the most significant method of recovery diagnosis. This research was conducted due to evaluating the effective factors of the sputum smear negative for pulmonary tuberculosis patients at the end of the second month of treatment.Methods: This cross-sectional study was conducted on 274 patients with smear positive pulmonary tuberculosis who were referred to health centers of Mashhad University of Medical Sciences from 2015 to 2016. Patients' demographics and clinical signs were extracted from their medical records and the effective factors of the sputum smear negativity at the end of the second month were evaluated by applying logistic regressionResults: At the end of the second month, 171 subjects (62.4 %) had smear negative, of whom 103 (60.2%) were women and 68 (64%) were men. In logistic regression, history of tuberculosis, the level of smear grade at the beginning of treatment and nationality are considered as significant factors.Conclusion: Smear grade at the beginning of treatment should be taken into account for pulmonary tuberculosis patients as the main marker of the response to treatment. However, by considering other factors, negative effects due to delay in treatment can be prevented.