Smoking and risk of liver cirrhosis: a population-based cohort study

Objective. Alcohol is the most acknowledged risk factor for liver cirrhosis. Smoking is rarely considered to be a cause of liver cirrhosis even though a few studies have suggested the opposite. The aim of this study was to assess the independent effect of smoking on alcoholic liver cirrhosis and liver cirrhosis in general. Materials and methods. The authors used data from the Copenhagen City Heart Study including a cohort of 9889 women and 8590 men from the Danish general population. Smoking and covariates were assessed at four consecutive examinations in 1976-78, 1981-83, 1991-94 and 2001-03. Updated measures were used in the analyses. Information on incident cases of alcoholic liver cirrhosis and liver cirrhosis was obtained from national hospital registries. Data were analyzed by means of Cox regression. Results. A total of 225 cases of alcoholic liver cirrhosis and 431 cases of liver cirrhosis occurred during follow-up. The hazard ratios (HR) of alcoholic liver cirrhosis was 3.9, 95% confidence interval (CI): 1.6, 9.4 for women and 1.6, 95% CI: 0.9, 3.0 for men smoking >10 g of tobacco per day compared with never-smokers. For liver cirrhosis, corresponding HRs were 2.2, 95% CI: 1.4, 3.4 for women and 1.4, 95% CI: 0.9, 2.2 for men. The HRs were adjusted for age, alcohol intake, education and body mass index. Conclusions. Smoking was associated with an increased risk of liver cirrhosis independent of alcohol intake.