Association of weight change following smoking cessation with the risk of tuberculosis development: A nationwide population-based cohort study

Abstract

Background: Smoking or weight loss is a risk of tuberculosis (TB) development. However, the impact of weight change after smoking cessation on the occurrence of TB remains elusive. We aimed to determine the relationship between weight change after smoking cessation and the risk of TB development.

Methods: We conducted a population-based cohort study using the national database in Republic of Korea. Of the 10,490,491 subjects who underwent health check-up in 2009, we enrolled 9,953,124 subjects without a previous TB history and followed them until 2017. We divided all study participants into the following three groups: never, former, and current smokers. The primary endpoint was newly developed TB.

Results: Among 9,953,124 subjects analyzed, 5,922,845 (59.5%) were never smokers, 1,428,209 (14.4%) were former smokers, and 2,602,080 (26.1%) were current smokers. The risk of TB development was significantly higher in current smokers than in never smokers (adjusted hazard ratio (aHR) 1.158; 95% confidence interval [CI] 1.131-1.186). Among current smokers, individuals who stopped smoking and maintained weight after baseline evaluation had a significantly lower risk of TB development compared with those who continued to smoke (aHR 0.771; 95% CI 0.741-0.892). However, even after smoking cessation, individuals who lost weight were at a significantly higher risk of TB development compared with those who continued to smoke (aHR 1.327; 95% CI 1.119-1.715).

Conclusions: Our findings suggest that smoking is a risk factor for TB and weight maintenance (neither gaining or losing) after quitting smoking might reduce the risk of TB development.

Fig 1. Flow chart of the study population.

9,943,124 participants were enrolled in this study. They were followed up until December 31, 2017. NHIS, national health insurance service.

Fig 2. Cumulative incidence curve of tuberculosis according to smoking status by Kaplan-Meier method and log-rank test (P < 0.0001).

Fig 3. Risk of tuberculosis development according to the cumulative amounts of cigarettes smoked.

Hazard ratios were adjusted for age, sex, alcohol consumption status, regular exercise, income level, and body mass index. Solid line indicates adjusted hazard ratios and dashed lines indicate 95% confidence interval, respectively. HR, hazard ratio.