Smoking as an independent risk factor of liver fibrosis in primary biliary cirrhosis

Background & Aims

Smoking has been identified as a potential predisposition factor for primary biliary cirrhosis (PBC). However, it remains unclear whether it is associated with more active and severe disease. Our aim was to assess the relationships between smoking and the severity of the elementary histological lesions, as well as the biochemical and immunological features of PBC.

Methods

Smoking history data were collected from 223 PBC patients using a standardized questionnaire. Histological data were available in 164 patients at presentation. Liver fibrosis and histological inflammatory activity were semi-quantified according to a METAVIR-based classification system. Odds ratios (OR) were assessed using a logistic regression analysis.

Results

Smoking history prior to diagnosis was reported in 58 patients (26%). Twenty-five patients (11%) were active smokers at diagnosis. Male gender (OR, 4.5), alcohol intake >20g/d (OR, 4.2), and F3–F4 fibrosis stage (OR, 2.7), but not inflammatory grade, bile duct changes, biochemical or immunological features, were associated with smoking history. Smoking intensity was significantly higher in patients with F3–F4 stage (8.1±14.2 pack-years vs. 3.0±7.0 pack-years; p=0.01). Adjusted logistic regression identified smoking history and smoking intensity as independent risk factors of advanced fibrosis. Each pack-year of increase in smoking intensity was associated with a 5.0% (95% CI, 1.3–8.7%) increased likelihood of advanced fibrosis.

Conclusions

Smoking increases, in a dose-dependent fashion, the risk of liver fibrosis in PBC without apparent increase in the histological inflammatory activity, bile duct lesions, biochemical, and immunological features of the disease. PBC patients should be strongly encouraged not to smoke.

Keywords: PBC, Smoking, Fibrosis, Autoimmunity