Background: Metabolic dysfunction-associated steatotic liver disease (MASLD), previously known as non-alcoholic fatty liver disease (NAFLD), is an increasingly prevalent liver disorder.
Objectives: This study investigated the effect of smoking status on various clinical outcomes in MASLD and metabolic dysfunction and alcohol-associated liver disease (MetALD).
Design: This study is a retrospective cohort analysis utilizing data from the UK Biobank (Application ID: 117214). Participants were categorized as current, previous, or never smokers, and outcomes were analyzed using inverse probability of treatment weighting to adjust for confounders.
Methods: The primary outcomes were all-cause mortality and liver-related mortality. Secondary outcomes included incidence of liver cirrhosis, hepatic decompensation, cardio-cerebrovascular diseases (CVD), and hepatocellular carcinoma (HCC). Multivariate Cox proportional hazards models were employed to evaluate associations.
Results: Previous and never smokers had significantly lower hazard ratios (HRs) for mortality compared to current smokers in all cohorts (HR: 0.33, 95% confidence interval (CI): 0.31-0.35, p < 0.001 for never smokers in No SLD cohort, HR: 0.43, 95% CI: 0.41-0.44, p < 0.001 for never smokers in MASLD cohort, and HR: 0.41, 95% CI: 0.38-0.45, p < 0.001 for never smokers in MetALD cohort). Previous and never smokers showed significantly lower incidences of liver cirrhosis compared to current smokers across all cohorts, except for MetALD. Previous and never smokers showed lower incidences of CVD compared to current smokers. In the MASLD cohort, never smokers had the lowest incidence of hepatic decompensation and HCC. In the MetALD cohort, no significant differences were observed in the risk of hepatic decompensation and HCC between different smoking statuses.
Conclusion: Smoking is related to worse survival outcomes and higher incidences of liver cirrhosis and CVD in MASLD and MetALD cohorts. Therefore, smoking cessation and prevention are crucial strategies for reducing the burden of liver disease and improving patient prognosis.
Keywords: liver cirrhosis; metabolic dysfunction-associated steatotic liver disease; smoking; survival.
How smoking affects health outcomes in people with metabolic liver diseases Why was the study done? Metabolic dysfunction-associated steatotic liver disease (MASLD), a common liver condition, can lead to serious health problems like liver failure, heart disease, and liver cancer. Smoking is a major health risk, but we do not fully understand how it affects people with MASLD or metabolic dysfunction and alcohol-associated liver disease (MetALD). This research was done to find out how smoking impacts survival and disease progression in people with these liver diseases so that doctors and healthcare providers can better support patients. What did the researchers do? The researchers used information from the UK Biobank, a large health study that follows many people over time. They compared three groups of people with MASLD or MetALD: those who currently smoke, those who quit smoking, and those who have never smoked. They looked at how smoking affects survival, liver-related health problems, and other illnesses like heart disease and strokes. What did the researchers find? The study found that people who smoke have a higher risk of dying from any cause or from liver disease than people who quit or never smoked. Smokers were also more likely to develop severe liver problems like liver cirrhosis, heart disease, and strokes. People who never smoked had the best health outcomes, with lower risks of liver and heart-related problems. However, for those with MetALD, alcohol use had a stronger effect on health than smoking. What do the findings mean? This study shows that quitting smoking—or never starting—can improve survival and reduce the risk of severe health problems in people with MASLD. It highlights the need for healthcare programs that support smoking cessation and prevention, especially for people with liver diseases. These efforts could save lives and improve quality of care for millions of people worldwide.
© The Author(s), 2025.