Noninvasive Diagnosis of Hepatic Steatosis Using Fat Attenuation Parameter Measured by FibroTouch and a New Algorithm in CHB Patients

Chronic hepatitis B (CHB) remains a major public health problem worldwide, and the prevalence of CHB patients with hepatic steatosis is gradually increasing. Noninvasive approaches for the assessment of hepatic steatosis have been developed as alternatives to liver biopsy. This study evaluated the diagnostic performance of the fat attenuation parameter (FAP) measured by transient elastography (FibroTouch) and a new algorithm to assess hepatic steatosis in CHB patients, in comparison to liver biopsy as the gold standard. Two hundred fifty-four CHB patients underwent simultaneous liver biopsy, biochemical blood testing, and FibroTouch examination. A new algorithm based on four factors (FAP; body mass index, BMI; high-density lipoprotein, HDL; apolipoprotein B, APOB) was defined as follows: fatty index = 10*ep/ (1+ep), and P = -2.75 + 0.028 ln FAP (dB/m) + 0.409 ln BMI (Kg/m2) - 2.482 ln HDL (mmol/L) + 1.979 ln APOB (g/L). The performances of FAP and fatty index were assessed by area under the ROC curve (AUROC). The difference in FAP was significant (P < 0.001) between CHB-only patients and CHB patients with hepatic steatosis. The cytokeratin 18 fragment (CK18-M65) level was significantly higher in CHB patients with non-alcoholic steatohepatitis (NASH) compared with CHB patients without NASH (P < 0.05). The optimal cutoff FAP values for hepatic steatosis of > 0, ≥ 5%, ≥ 10%, ≥ 20%, and ≥ 30% were 224.1, 230.6, 235.5, 246.9, and 261.1 dB/m, and AUROCs were 0.833, 0.801, 0.915, 0.917, and 0.972, respectively. The optimal cutoff value of fatty index for the diagnosis of hepatic steatosis was 1.5 and the AUROC was 0.807. FAP is an accurate, reliable, and noninvasive approach that can also be combined with other metabolic biomarkers to comprehensively detect and quantify hepatic steatosis.