Controlled attenuation parameter (CAP) for detection of hepatic steatosis in patients with chronic liver diseases: A prospective study of a native Korean population

Background: Controlled attenuation parameter (CAP) is a non-invasive method of measuring hepatic steatosis using a process based on transient elastography. We investigated the diagnostic accuracy of CAP in detecting hepatic steatosis in patients with chronic liver disease (CLD). Methods: A total of 135 patients with CLD who underwent liver biopsy and CAP were consecutively enrolled in this prospective study. The performance of CAP for detection of hepatic steatosis compared with liver biopsy was calculated using area under receiver operating characteristics curves (AUROC). Steatosis was categorized into S0 (<5%), S1 (5-33%), S2 (34-66%) and S3 (>66% of hepatocytes). Results: Male gender predominated (n = 87, 64%) and the median age was 51 years. The aetiologies of CLD included non-alcoholic fatty liver disease (n = 56, 41.5%) and chronic viral hepatitis because of hepatitis B (n = 47, 34.8%) and C (n = 12, 8.9%). Steatosis repartition was: S0 31.1% (n = 42), S1 43.7% (n = 59), S2 18.5% (n = 25) and S3 6.7% (n = 9) respectively. In the multivariate analysis, steatosis grade and body mass index were independently associated with CAP (all P < 0.001), whereas fibrosis stage and activity grade were not. The AUROCs of CAP were 0.885 for ≥S1 (sensitivity 73.1%, specificity 95.2%), 0.894 for ≥S2 (sensitivity 82.4%, specificity 86.1%) and 0.800 for S3 (sensitivity 77.8%, specificity 84.1%). The optimal cut-off CAP values that maximized the Youden index were 250 dB/m (≥S1), 299 dB/m (≥S2), and 327 dB/m (=S3) respectively. Conclusions: Our data showed that CAP had high diagnostic accuracy for detecting hepatic steatosis in patients with CLD and suggested that CAP is also applicable for Asian patients.