Abstract

Background/Aims
In adults with steatotic liver disease (SLD), the hepatic impact of transitioning between combustible cigarettes (CCs) and noncombustible nicotine or tobacco products (NNTPs) remains unclear. We examined CC-NNTP transitions and liver-related events (LREs).
Methods
From the Korean National Health Insurance Service, 502,198 adults with SLD and at least one cardiometabolic risk factor completing health screenings during both 2012-2013 and 2019-2020 were followed through December 2023. Seven mutually exclusive groups were defined by CC status and NNTP use; the primary outcome was LRE, including hepatocellular carcinoma and liver cirrhosis. Cox proportional hazards regression, propensity-score matching (PSM), and counterfactual mediation analysis were performed.
Results
Among 502,198 participants (mean age 57.9 years; 65.6% male), 2,549 LREs occurred over a median 3.0-year follow-up. Compared with never-smokers, continuous CC smokers without NNTP use had the highest LRE risk (aHR, 1.51; 95% confidence interval (CI), 1.34-1.70), followed by CC initiators (1.45; 1.17-1.79) and CC quitters (1.28; 1.12-1.46) without NNTPs. CC quitters with NNTP use showed a lower LRE risk than continuous CC smokers without NNTP use in the full cohort (aHR, 0.65; 95% CI, 0.43-0.99), but this association was not statistically significant under PSM (aHR, 0.65; 95% CI, 0.39-1.09). Within-group PSM of NNTP versus nonuse was nonsignificant across all CC categories.
Conclusions
CC cessation was associated with lower LRE risk than continued CC smoking, even among those who transitioned to NNTPs. However, NNTP use showed no independent protective association, supporting complete tobacco/nicotine abstinence as the preferred goal.

• Keywords: metabolic-dysfunction-associated steatotic liver disease; e-cigarettes; smoking cessation; liver cirrhosis; hepatocellular carcinoma