CLINICAL AND BIOCHEMICAL CHARACTERISTICS IN NONALCOHOLIC FATTY LIVER IN LEAN AND NON-LEAN MALE AND FEMALE PATIENTS ACCORDING TO ASIA-PACIFIC BASAL METABOLIC INDEX CRITERIA IN A TERTIARY CARE HOSPITAL, WEST BENGAL– A CROSS SECTIONAL OBSERVATIONAL STUDY

Introduction: Nonalcoholic fatty liver disease (NAFLD) represents a metabolic spectrum ranging from simple steatosis to cirrhosis and hepatocellular carcinoma. Although classically associated with obesity, lean individuals particularly in Asian populations are increasingly affected due to higher visceral adiposity at lower body mass index (BMI). The Asia-Pacific guideline defines lean as BMI <23 kg/m² and non-lean as ≥23 kg/m², reflecting region-specific metabolic risk. Aims and Objectives: To compare clinical, biochemical, and fibrosis-related characteristics including triglyceride-glucose (TyG) index, TyG-BMI, and triglyceride/HDL ratio—among lean and non-lean male and female NAFLD patients, and to evaluate the diagnostic accuracy of non-invasive fibrosis indices (FIB-4, APRI, TyG). Materials and Methods: A cross-sectional retrospective analysis was performed on 497 NAFLD patients (271 males, 226 females) attending a tertiary care hospital in West Bengal. Demographic data, liver enzymes, lipid and glucose profiles, and FibroScan liver stiffness were collected. Derived indices (FIB-4, APRI, TyG, TyG-BMI) were calculated. Statistical analysis included Welch’s t-test, Mann–Whitney U test, chi-square test, effect size estimation, and ROC analysis. Results: Non-lean males exhibited higher triglycerides, LDL cholesterol, and TyG indices, while non-lean females showed higher FIB-4 and BARD scores. Liver stiffness ≥8 kPa was more prevalent in non-lean patients of both sexes. ROC analysis demonstrated TyG (AUC ≈0.85) and FIB-4 (AUC ≈0.80) as the best predictors of significant fibrosis, each with a negative predictive value of approximately 88%. Conclusion: BMI ≥23 kg/m² effectively stratifies metabolic and fibrotic risk in Indian NAFLD patients. TyG and FIB-4 are simple, cost-effective tools for early fibrosis screening, supporting the clinical relevance of the Asia-Pacific BMI cut-off.