Objective  To explore the impact of smoking upon therapeutic outcome among smear-positive pulmonary tuberculosis (TB) patients.

  Methods  We recruited 2 038 smear-positive TB patients diagnosed and completing TB therapy from 2008 through 2011 in 49 TB dispensaries or medical institutions designated for medication of TB patients in 8 provinces across China; then we assigned the patients into three groups of current smoker, ex-smoker, and never smoker. Disparities in lesion resorption, cavity closure, sputum-culture negative conversion, and treatment outcome were compared among the three groups with Chi-square test. Unconditional logistic regression analysis was adopted to assess influences of smoking on therapeutic outcomes among the patients.

  Results  Of all the patients, 17.4%, 36.1%, and 46.5% were current smoker, ex-smoker, and never smoker, respectively. There were significant differences in sputum-culture negative conversion by the end of 2-month medication (χ² = 9.045, P = 0.011) and treatment outcome (χ² = 17.130, P = 0.008) among the three groups. In comparison with the current smokers, the ex-smokers were more likely to have sputum-culture positive by the end of 2-month medication (odds ratio OR = 1.376, 95% confidence interval 95% CI: 1.102 – 1.871) and treatment failure (OR = 1.183, 95% CI: 1.021 – 1.929); compared to never smokers, the current smokers were more likely to have sputum-culture positive by the end of 2-month medication (OR = 1.657, 95% CI: 1.137 – 2.414) and treatment failure (OR = 1.325, 95% CI: 1.023 – 2.308).

  Conclusion  Smoking has adverse impact on outcome of TB treatment and could increase sputum-culture positive rate by the end of 2-month medication, treatment failure and death rate among smear-positive pulmonary tuberculosis patients.