IDENTIFYING NON-ALCOHOLIC FATTY LIVER DISEASE AMONG ASYMPTOMATIC OVERWEIGHT AND OBESE INDIVIDUALS BY CLINICAL AND BIOCHEMICAL CHARACTERISTICS

Abstract

Objective: To determine the prevalence of liver steatosis among asymptomatic individuals attending an out-patient clinic for a problem of overweight, and to define the discriminatory value of several characteristics for predicting liver steatosis among them.

Design and participants: Consecutive patients with a body mass index (BMI) of ≥ 25 kg/m² who consented to undergo liver ultrasound and blood tests were recruited for inclusion. Receiver operating characteristic (ROC) curves were generated and statistical indices of diagnostic performance and their corresponding 95% confidence intervals (95% CI) were computed. Logistic regression analyses were performed to determine whether a combination of characteristics could improve diagnostic accuracy.

Results: We enrolled sixty-eight subjects (mean BMI, 37.5 kg/m²), of whom 39 (57.4%) had liver steatosis on ultrasound. Logistic regression analyses indicated that only 3 variables were significantly and independently correlated with liver steatosis: female gender, low adiponectin levels, and high insulin resistance index. A composite index for predicting liver steatosis was calculated by summing the risk factors of female gender, low adiponectin, and insulin resistance index (FAIR score). The accuracy of this score was determined by ROC analysis to be 0.85 (95% CI, 0.74-0.96; P < 0.001). The presence of two or more risk factors (FAIR score > 2) had a sensitivity, specificity, positive predictive value, and negative predictive value of 77%, 91%, 92%, and 74%, respectively. The likelihood ratio for a positive result was 8.43.

Conclusions: Among asymptomatic overweight individuals attending an out-patient clinic, the prevalence of liver steatosis on ultrasound is 57%. Female gender, the insulin resistance index, and low adiponectin are significant and independent predictors of liver steatosis. A combination of these three factors allows sensitivity and specificity for non alcoholic fatty liver of 77 % and 91 %, respectively.

Keywords:

• non-alcoholic fatty liver disease
• adiponectin
• leptin
• prediction
• receiver operating characteristic (ROC) curves

Keywords:

• Abbreviations: NAFLD, non-alcoholic fatty liver disease
• NASH, non-alcoholic steatohepatitis
• BMI, body mass index
• ROC, receiver operating characteristic
• AUC, area under the curve
• TSH, thyroid stimulating hormone
• IGF-1, insulin-like growth factor-1
• TIBC, total iron binding capacity
• AST, aspartate aminotransferase
• ALT, alanine aminotransferase
• AP, alcaline phosphatase
• γ-GT, gamma-glutamyltransferase
• HDL, high density lipoprotein
• LDL, low density lipoprotein
• QUICKI, quantitative insulin sensitivity check index
• IR-index, insulin resistance index