Central Obesity is an Independent Determinant of Advanced Fibrosis in Lean Patients With Nonalcoholic Fatty Liver Disease

Background: The current definition of lean 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 lean patients with nonalcoholic fatty liver disease (NAFLD) with and without CO. Methods: One hundred seventy lean patients with NAFLD (BMI <23 kg/m(2)) were divided into two groups depending upon the presence or absence of CO (waist circumference >= 80 cm in females and >= 90 cm in males). Noninvasive 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: Of 170 patients with lean NAFLD, 96 (56.5%) 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 the CO group. There was a poor correlation between BMI and waist circumference (r = 0.24, 95% CI: 0.09-0.38). 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 those with 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 after adjusting for BMI and metabolic risk factors (aOR: 3.11 (1.10-8.96), P = 0.03). Among these 170 patients, 142 fulfilled metabolic dysfunction associated steatotic liver disease (MASLD) criteria. CO was also an independent risk factor for advanced fibrosis in MASLD (3.32 (1.23-8.5), P = 0.02). Conclusion: Lean patients with NAFLD or MASLD and CO have more severe liver disease compared to those without CO.