Non-invasive diagnosis of liver steatosis using controlled attenuation parameter (CAP) and transient elastography

Recently, a study showed that Controlled Attenuation Parameter (CAP), evaluated with transient elastography, could efficiently separate steatosis grades. The aim of this study was to prospectively evaluate the performance of CAP for the diagnosis of steatosis in patients with chronic liver disease.

Consecutive patients with chronic liver disease had steatosis diagnosis using CAP, blood sample and liver biopsy. Steatosis was graded as the percentage of hepatocytes with fat: S0 ≤ 10%, S1: 11 ~ 33%, S2: 34 ~ 66%, S3 ≥ 67%.

Characteristics of the 112 patients included were as follows: age 54 years, BMI 26 kg m(-) ², HCV 36%, NAFLD 25%. Steatosis repartition was: S0 52%, S1 19%, S2 14%, S3 15%. CAP was significantly correlated with SteatoTest, Fatty Liver Index (FLI), percentage of steatosis on liver biopsy, steatosis grade and slightly with liver stiffness, but not with fibrosis and activity grade on liver biopsy. Using CAP vs SteatoTest vs FLI score, Area Under the Receiver-Operating Characteristics (ROC) curves (AUROC)s were 0.84 vs 0.72 vs 0.72 for the diagnosis of steatosis ≥ S1, 0.86 vs 0.73 vs 0.71 for the diagnosis of steatosis ≥ S2, and 0.93 vs 0.73 vs 0.75 for the diagnosis of steatosis S3 respectively. For a sensitivity ≥ 90%, cut-offs of CAP were 215 dB m(-1) for S ≥ 1, 252 dB m(-1) for S ≥ 2, and 296 dB m(-1) for S3.

CAP is very efficient to detect even low grade steatosis. CAP being implemented on FibroScan(®) (Echosens, Paris, France), both steatosis and fibrosis can be evaluated simultaneously, enlarging the spectrum of non-invasive techniques for the management of chronic liver diseases.