Clinicopathological study of nonalcoholic fatty liver disease in Japan: the risk factors for fibrosis

BACKGROUND/AIMS: We evaluated patients with nonalcoholic fatty liver disease (NAFLD) and compared the clinical and pathological features to identify the risk factors for NAFLD with severe fibrosis. METHODS: One hundred and eighty-two patients with biopsy-confirmed NAFLD from various medical centres were recruited into this study. RESULTS: The variables that were significantly associated with severe steatosis were male gender (mild:severe=36%:53%, P=0.02), younger age (mild:severe=57%:82%, P>0.001) and absence of type 2 diabetes (mild:severe=43%:71%, P>0.001). There was no significant difference in the degree of inflammation among the clinical groups. The variables that were significantly associated with severe fibrosis were female gender (mild:severe=54%:84%, P=0.002), older age (> or = 60 years old) (mild:severe=29%:53%, P=0.020), type 2 diabetes (mild:severe=42%:71%, P=0.020) and hypertension (mild:severe=24%:53%, P=0.002). Although there were more obese patients in the group with severe fibrosis, the association was not statistically significant (mild:severe=67%:78%, P=0.229). The prevalence of high serum triglyceride levels was similar between the two groups. The N (Nippon) score (total number of risk factor) could significantly predict severe fibrosis in NAFLD patients (1.48 +/- 1.14 vs. 2.66 +/- 0.94, P<0.001). CONCLUSIONS: The N score can be used to predict severe fibrosis in cases of NAFLD.