Interobserver concordance in controlled attenuation parameter measurement, a novel tool for the assessment of hepatic steatosis on the basis of transient elastography

Background The combination of transient elastometry with a controlled attenuation parameter (CAP) is available to evaluate hepatic steatosis (HS) along with liver stiffness. Aims To assess the concordance of CAP measurements between two independent observers in patients infected by HIV and/or hepatitis virus, as well as to determine the concordance of classification of the grade of HS using two cut-off values. Materials and methods In a cross-sectional prospective study, CAP-enabled transient elastometry acquisitions were performed by two independent observers in patients with HIV or hepatitis virus infection. The interobserver concordance between the CAP examinations was assessed using the intraclass correlation coefficient and the concordance in the classification of patients in the grades of HS was characterized using the index. Results A total of 118 patients were included. Twenty (17%) patients were HIV monoinfected, 44 (37.3%) were hepatitis C virus monoinfected, and 52 (44%) had HIV/hepatitis C virus coinfection. The median (Q1-Q3) of the absolute difference of CAP values between the two observers was 20 (10-41) dB/m. The overall intraclass correlation coefficient was 0.84 (95% confidence interval: 0.77-0.88). The corresponding figures for liver stiffness measurements were 0.9 (0.4-2.6) kPa and 0.96 (95% confidence interval: 0.94-0.97). The indexes for the concordance of classification for the presence of HS, cut-off of 215 dB/m, and significant HS, cut-off of 252 dB/m, were 0.53 and 0.62, respectively. Conclusion The determination of HS by means of CAP in HIV and/or hepatitis virus infection represents an observer-independent and easily performable method. However, the use of cut-off values for the classification of patients is suboptimal. (C) 2013 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins.