Central Obesity Is Independently Associated With Advanced Fibrosis in Lean NAFLD

Introduction: The current definition of lean NAFLD is based on body mass index (BMI). However, BMI is an imperfect surrogate for adiposity and provides no information on central obesity (CO). Hence, we explored the differences in clinical profile and liver disease severity in Indian lean patients with NAFLD with and without CO. Methods: 171 lean patients with NAFLD were divided into 2 groups depending upon the presence or absence of CO (waist circumference ≥80 cm in females and ≥90 cm in males). Non-invasive assessment of steatosis was done by ultrasound and controlled attenuation parameter (CAP) while fibrosis was assessed with FIB-4 and liver stiffness measurement (LSM). FibroScan-AST (FAST) score was used for non-invasive prediction of NASH with significant fibrosis. Results: Ninety-six (56.5%) patients had CO. Female gender (40.6% vs 17.6%, P=0.001), hypertriglyceridemia (58.3% vs 39.2%, P=0.01) and metabolic syndrome (23.9% vs 4.1%, P< 0.001) were more common in CO group. However, there was no difference in serum HDL, fasting blood glucose, HbA1c, diabetes mellitus or hypertension. There was a poor correlation between BMI and waist circumference (r=0.24, 95% CI: 0.09-0.38). Transaminase levels were similar. Grade 2-3 steatosis on ultrasound was significantly more common in CO patients (30% vs 12.3%, P=0.007). CAP [312.5 (289.8-341) dB/m vs 275 (248-305.1) dB/m, P=0.002], FAST score [0.42 (0.15-0.66) vs 0.26 (0.11-0.39), P=0.04], FIB-4 and LSM were higher in CO. Advanced fibrosis was more prevalent among CO patients using FIB-4 (19.8% vs 8.1%, P=0.03) and LSM (9.5% vs 0, P=0.04). CO was independently associated with advanced fibrosis (aOR: 3.11 (1.10-8.96), P=0.03) after adjusting for BMI, dyslipidemia, hypertension and diabetes. Conclusion: Lean NAFLD patients with CO have more severe liver disease compared to those without CO. Both BMI and waist circumference may be considered for defining lean NAFLD as suggested by the recent guidance document of the Indian National Association for the Study of the Liver (INASL).