Assessment of Insulin Resistance in Ultrasonographically Diagnosed Cases of Non-Alcoholic Fatty Liver Disease BC13-BC17
Dr. Sharmistha Chatterjee,
181B/1, Kabi Guru Sarani, Kolkata-700038, West Bengal, India.
Introduction: Non-Alcoholic Fatty Liver Disease (NAFLD) is the excessive accumulation of fat primarily in form of triacylglycerols in more than 5% of the hepatocytes without significant consumption of alcohol and other known causes of steatosis. Literature suggests an association of NAFLD with Insulin Resistant (IR) Metabolic Syndrome (MetS). In clinical settings, ultrasonography is commonly used for diagnosis of NAFLD as opposed to expensive biopsy procedures.
Aim: To assess the diagnostic utility of the surrogate markers of IR in ultrasonographically diagnosed cases of NAFLD.
Materials and Methods: The cross-sectional study was carried out at College of Medicine and Sagore Dutta Hospital (CMSDH), Tertiary Care Hospital and Teaching Institute in Kolkata, West Bengal, India. Ultrasonographically diagnosed 116 cases (aged 32-65 years) of NAFLD were selected and 100 apparently healthy age and sex-matched individuals were recruited as controls. Overnight fasting blood samples were analysed for fasting glucose, insulin, glycated haemoglobin (HbA1C), lipid profile and transaminases levels. IR was estimated with the Homeostasis Model Assessment index for Insulin Resistance (HOMA-IR). One-way analysis variance (ANOVA) was used for normally distributed data and Kruskal Wallis for a non-parametric data. Receiver Operator Curve (ROC) were generated to identify the cut-off values of HOMA-IR, Aspartate aminotransferase (AST), Alanine aminotransferase (ALT), the AST/ALT ratio and fasting triglycerides to predict the existence of fatty liver. Adjusted Odds Ratio (OR) was also calculated to measure the independent effect of the risk factors.
Results: Statistically significant differences were observed in insulin (p-value=0.033), HOMA-IR (p-value=0.049), triglycerides (p-value=0.00008), HbA1C (p-value=0.030), AST/ALT ratio (p-value=0.012), AST (p-value=0.015), ALT (p-value 0.00001) levels among cases and controls. The predictive cut-off for possibility of existence of fatty liver was HOMA-IR was >2.9 (sensitivity was 63.27%, specificity of 93.94), triglycerides =137 mg/dL, (60.67% sensitivity and 60.98% specificity) and AST/ALT ratio of 0.74 (specificity of 65.15% and a sensitivity of 62.50%). For HOMA-IR >2.5, the relative risk was 5.56 and OR was 7.15. For triglycerides >150 mg/dL, the relative risk was 1.88 and OR was 2.87.
Conclusion: While ultrasound remains method of choice for diagnosis of NAFLD, assessment of parameters like IR, AST/ALT ratio aids in detection of associated MetS such as Cardiovascular Disorders (CVD) and Diabetes Mellitus (DM) that warrants proper lifestyle modification and therapeutic intervention.