Published online Apr 28, 2014. doi: 10.3748/wjg.v20.i16.4702
Revised: December 25, 2013
Accepted: February 26, 2014
Published online: April 28, 2014
AIM: To evaluate the performance of a novel non-invasive controlled attenuation parameter (CAP) to assess liver steatosis.
METHODS: This was a multi-center prospective cohort study. Consecutive patients (aged ≥ 18 years) who had undergone percutaneous liver biopsy and CAP measurement were recruited from three Chinese liver centers. Steatosis was categorized as S0: < 5%; S1: 5%-33%; S2: 34%-66%; or S3: ≥ 67%, according to the nonalcoholic fatty liver disease (NAFLD) activity score. The FibroScan® 502 equipped with the M probe (Echosens, Paris, France) was used to capture both CAP and liver stiffness measurement values simultaneously. Receiver operating characteristic curves were plotted, and the areas under the curves were calculated to determine the diagnostic efficacy. The accuracy of the CAP values at the optimal thresholds was defined by maximizing the sum of sensitivity and specificity (maximum Youden index).
RESULTS: A total of 152 patients were recruited, including 52 (34.2%) patients with NAFLD and 100 (65.8%) with chronic hepatitis B (CHB) virus infection. After adjustment, the steatosis grade (OR = 37.12; 95%CI: 21.63-52.60, P < 0.001) and body mass index (BMI, OR = 6.20; 95%CI: 2.92-9.48, P < 0.001) were found independently associated with CAP by multivariate linear regression analysis. CAP was not influenced by inflammation, fibrosis or aetiology. The median CAP values and interquartile ranges among patients with S0, S1, S2 and S3 steatosis were 211 (181-240) dB/m, 270 (253-305) dB/m, 330 (302-360) dB/m, and 346 (313-363) dB/m, respectively. The cut-offs for the CAP values in all patients with steatosis ≥ 5%, ≥ 34% and ≥ 67% were 253 dB/m, 285 dB/m and 310 dB/m, respectively. The areas under the curves were 0.92, 0.92 and 0.88 for steatosis ≥ 5%, ≥ 34% and ≥ 67%, respectively. No significant differences were found in the CAP values between the NAFLD group and the CHB group in each steatosis grade.
CONCLUSION: CAP appears to be a promising tool for the non-invasive detection and quantification of hepatic steatosis, but is limited by BMI.
Core tip: We introduced a novel controlled attenuation parameter (CAP) which was acquired using the FibroScan® equipped with the M probe. This multi-center prospective cohort study was performed in Chinese nonalcoholic fatty liver disease or chronic hepatitis B patients. Following multivariate linear regression analysis, we found that CAP was significantly correlated with steatosis grade and was not influenced by inflammation, fibrosis or aetiology. Although it is less effective in identifying moderate to severe steatosis and limited by body mass index, we believe that CAP values are more useful than the measurement of 5% steatosis and may be used as a substitute for ultrasonography in epidemiological investigations of fatty liver.