Characteristics of non‐alcoholic steatohepatitis among lean patients in Japan: Not uncommon and not always benign. Issue 8 (15th January 2019) - Tobari, Maki
Abstract: Background and Aim: To elucidate features of nonobese non‐alcoholic fatty liver disease (NAFLD), we assessed Japanese patients with NAFLD stratified by body mass index (BMI) and by sex. Methods: Biopsy‐proven 762 NAFLD patients (404 men) were classified into three groups by the Japanese criteria: nonobese group (BMI < 25 kg/m 2 ), obese group (25 to 30), and severely obese group (≥ 30). Clinicopathological features and single nucleotide polymorphism of patatin‐like phospholipase 3 ( PNPLA3 ) rs738409 were investigated, and body composition analysis was performed by bioelectrical impedance analysis and computed tomography. Results: Over 25% of men and almost 40% of women were nonobese, but most of them had visceral fat obesity and/or insulin resistance. The median age (years) of the nonobese, obese, and severely obese men was 49.9, 46.8, and 40.5 ( P < 0.01), respectively, while those of women was 60.2, 59.6, and 48.5 ( P < 0.01), respectively. The prevalence of metabolic comorbidities and PNPLA3 risk alleles did not differ among these groups in both sexes. Also, the prevalence of non‐alcoholic steatohepatitis was not significantly different in both sexes, although nonobese patients had a higher prevalence of mild steatosis. Advanced fibrosis showed a marked difference between men and women. Advanced fibrosis was significantly more frequent among severely obese men (nonobese: 31.0%, obese: 41.6%, severely obese: 60.9%; P < 0.01), but it was lower among severely obese women (51.4%, 62.9%, 33.7%; P < 0.01). Skeletal muscle mass was significantly lower in nonobese patients. Conclusions: Non‐alcoholic fatty liver disease was not milder in nonobese patients. Histological steatosis was associated with BMI, but advanced fibrosis was not and showed a significant sex difference.