Smoking is associated with severity of liver fibrosis but not with histological severity in nonalcoholic fatty liver disease. Results from a cross-sectional study

Objectives: To assess the influence of smoking on histological disease severity and fibrosis in real-world NAFLD patients.Material and methods: Consecutive NAFLD patients were identified with liver biopsies performed between 2008 and 2015. Characteristics such as smoking status and total number of pack years were collected. Biopsies were revised and BRUNT fibrosis and NAFLD activity score (NAS) determined. Patients with a high NAS (5) were compared to patients with a low NAS (<5) and with advanced fibrosis (stage 3-4) to patients with no-early fibrosis (stage 0-2). Patients with a history of smoking (current or past smoker) were defined ever smokers.Results: Fifty-six patients were included (mean age 4914.3, 68.9% males and 39.3% history of smoking). Ever smokers had a higher fibrosis score than never smokers; two (IQR 0-3) versus one (IQR 1-1.5) (p=.040). Patients with advanced fibrosis smoked significantly more pack years than patients with no-early fibrosis; 10.6 (IQR 0-25.8) versus 0 (IQR 0-7) (p=.011). There is a weak to moderate correlation between fibrosis stage and number of pack years (Spearman's Rho=0.341, p=.012). There was no difference in NAS between never and ever smokers; 2.8 +/- 1.5 versus 3.3 +/- 1.4 (p=.205). Patients with NAS <5 had a median number of pack years of 0 (IQR 0-9) versus a median of 10.3 pack years (IQR 0-24) in patients with NAS 5 (p=.127).Conclusion: Smoking is associated with severity of NAFLD-related liver fibrosis but not with histological disease severity. This supports the recommendation to cease smoking for NAFLD patients.