Association between tobacco smoking and TB

Smoking is a significant risk factor for tuberculosis (TB) in South Korea, with current smokers exhibiting a higher incidence rate (0.60%) compared to never smokers (0.56%) and former smokers (0.59%). After adjusting for confounding variables, current smokers had a notably increased TB risk (aHR 1.158; 95% CI 1.130–1.186), whereas former smokers showed a reduced risk (aHR 0.947; 95% CI 0.921–0.973) compared to never smokers. A dose-response relationship was evident, as TB risk increased with both smoking intensity (higher packs per day) and duration (longer years of smoking).[1]

Smoking cessation plays a crucial role in reducing TB risk, particularly when weight is maintained after quitting. Former smokers who had consumed less than one pack per day showed a lower TB risk than never smokers, whereas those who had smoked more than one pack per day did not experience this protective effect. Notably, weight maintenance after smoking cessation significantly lowered TB risk (aHR 0.771; 95% CI 0.741–0.892) compared to continued smokers, regardless of weight changes. However, individuals who lost weight after quitting smoking had an increased TB risk, similar to those who continued smoking and also experienced weight loss (aHR 1.389–1.401). Given these findings, smoking cessation is highly recommended to reduce TB risk, with an emphasis on maintaining a stable weight post-cessation.[1]

Current smoking is associated with a twofold increase in active TB risk compared to never-smokers, with the risk escalating based on cigarette consumption, years of smoking, and pack-years. Smoking contributes to 17% of TB cases in the studied population in Taiwan, underscoring its significant role in TB incidence. Notably, current smokers face a higher TB risk than former smokers, suggesting that quitting smoking reduces this hazard. The impact of smoking-related TB is more pronounced in individuals under 65, possibly due to the early depletion of susceptible populations among older smokers. This elevated risk is largely attributed to smoking-induced impairment of key pulmonary defense mechanisms, which increases susceptibility to TB upon exposure to the pathogen.[2]

References:

1. Kim, S.H., Park, Y.M., Han, K., Ko, S.H., Kim, S.Y., Song, S.H., Kim, C.H., Hur, K.Y. and Kim, S.K., 2022. Association of weight change following smoking cessation with the risk of tuberculosis development: A nationwide population-based cohort study. Plos one, 17(4), p.e0266262.

2. Lin, H.H., Ezzati, M., Chang, H.Y. and Murray, M., 2009. Association between tobacco smoking and active tuberculosis in Taiwan: prospective cohort study. American journal of respiratory and critical care medicine, 180(5), pp.475-480.