Non-obese histologically confirmed NASH patients with abnormal liver biochemistry have more advanced fibrosis

Background and aims Non-alcoholic fatty liver disease (NAFLD) commonly affects subjects with obesity, yet non-obese NAFLD is increasingly being recognized. We aimed to investigate the clinicopathological and genetic characteristics of non-obese NAFLD patients. Methods The clinical, histological and genetic data of 84 NAFLD patients with biopsy for abnormal liver function test were reviewed. Both NAS-CRN and SAF scoring systems were applied for histopathological evaluation. PNPLA3 and TMS6F2 genotyping were also performed. Results All of the 84 patients were histologically diagnosed with non-alcoholic steatohepatitis (NASH), with 36 of them (42.9%) being non-obese (BMI < 25 kg/m2). Compared with the obese group, non-obese group were predominantly females (88.9% vs 52.1%, p < 0.001), tended to have higher prevalence of diabetes (p = 0.068). More importantly non-obese patients had a significant higher prevalence of advanced fibrosis (F = 3) (58.3% vs 29.2%, p = 0.013), and a trend of higher degree of ballooning (p = 0.061). In addition, values of liver stiffness measurement were also significantly higher in non-obese group (12.1 kPa vs 8.1 kPa, p = 0.032). There was also a trend of higher prevalence of TM6SF2 T allele in non-obese group (p = 0.085), while the prevalence of PNPLA3 risk allele did not differ between two groups. Multivariate analysis showed that higher fasting glucose (p = 0.038) and lower serum platelets (p = 0.040) were two independent predictors for advanced fibrosis in non-obese patients. Conclusions Non-obese NASH patients have a female predominance and more advanced fibrosis. Liver biopsy is crucial to evaluate the severity of disease in non-obese patients especially those with abnormal liver biochemistry. Clinical trial number NCT03386890.