Background: The prognostic factors of morbidity and mortality in patients with lean NAFLD (body mass index < 25.0 kg/m2) are unknown.
Methods: In this retrospective study, 446 Japanese patients with histopathologically-confirmed NAFLD (lean NAFLD, n = 170) were followed for liver events, cardiovascular events, type 2 diabetes mellitus, and non-liver malignancies. The median observation period was 4.6 years. We also investigated the predictors of severe fibrosis (stage 3-4) and mortality in lean NAFLD patients.
Results: Glycolipid metabolic markers, liver function tests, NAFLD fibrosis score (NFS), and histological scoring were significantly lower in lean NAFLD patients than in non-lean NAFLD. The incidence of liver cancer was higher while that of T2DM was lower in lean NAFLD. Kaplan-Meier analysis showed no significant difference in overall survival between the lean and non-lean NAFLD. Multivariate analysis of data of lean NAFLD identified NFS ≥ - 1.455 as significant independent predictor of severe fibrosis, while history of liver cancer and NFS ≥ - 1.455 were predictors of overall survival.
Conclusions: Although patients with lean NAFLD have better histopathological and biochemical profile compared to patients with non-lean NAFLD, the prognosis is not different between the two groups. Lean NAFLD patients with NFS ≥ - 1.455 or history of liver cancer should be monitored carefully during follow-up.
Keywords: Fibrosis; Lean NAFLD; Liver cancer; Mortality; NAFLD; NAFLD fibrosis score; NASH; NFS; Overall survival; Prognosis.