How Do Smoking Status and Smoking Cessation Efforts Affect TB Recurrence After Successful Completion of Anti-TB Treatment? A Multicenter, Prospective Cohort Study With a 7-Year Follow-up in China

Abstract

Introduction: Many important risk factors are associated with tuberculosis (TB) recurrence; among them, smoking is the most common and modifiable behavioral factor. We aimed to assess the association of smoking status and cessation support during anti-TB treatment with subsequent TB recurrence.

Aims and methods: A 7-year prospective cohort study was performed on 634 TB patients in China. The participants were grouped by smoking status at baseline. Cox proportional hazards models were applied to analyze the association between baseline characteristics and TB recurrence. The cumulative incidence of TB recurrence was estimated by Kaplan-Meier curves.

Results: Multivariable analysis showed that patients who continued smoking during anti-TB treatment were at higher risk for TB recurrence (hazard ratio = 3.45; 95% confidence interval: 1.54-7.73) than nonsmokers. Moreover, this risk remained significant even in those who stopped smoking during anti-TB treatment (hazard ratio = 2.75; 95% confidence interval: 1.47-5.14) than nonsmokers. The association between smoking and TB recurrence was stronger for smear-positive TB patients than for smear-negative TB patients. Among all the subgroups, patients who continued smoking had a higher TB recurrence rate over the 7-year follow-up than those who successfully quit during their anti-TB treatment (log-rank statistic, p < .01). With the increase in the number of cigarettes smoked daily, the TB recurrence risk also increased accordingly (log-rank statistic, p = .02).

Conclusions: Our findings highlight the importance of incorporating effective smoking cessation intervention measures into TB services and call for continuous monitoring of TB recurrence. Among patients who continue smoking or have a history of smoking, special attention should be given to smear-positive patients and heavy smokers when monitoring recurrence.

Implications: This study provides a comprehensive picture of the association of smoking behavior and cessation efforts with TB recurrence. It shows that patients who are nonsmokers have the lowest risk of recurrence and that ex-smokers have a lower risk of recurrence than current smokers. Moreover, patients who successfully quit smoking during TB treatment have a lower risk of recurrence than those who continue smoking. Health workers should provide cessation intervention, focus on TB patients with a history of smoking, and continuously monitor TB recurrence after the completion of anti-TB treatment, particularly for smear-positive TB patients.