title: Interobserver concordance in controlled attenuation parameter measurement, a novel tool for the assessment of hepatic steatosis on the basis of transient elastography.
abstract: BACKGROUND
  The combination of transient elastometry with a controlled attenuation parameter (CAP) is available to evaluate hepatic steatosis (HS) along with liver stiffness.
  
  
  OBJECTIVE
  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.
  
  
  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 κ 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 κ 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.
  
  
  CONCLUSIONS
  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.
authors: Unit of Infectious Diseases and Microbiology, Hospital Universitario de Valme, Seville, Spain.
authors: Eva
authors: E
authors: Recio
authors: Celia
authors: C
authors: Cifuentes
authors: Juan
authors: J
authors: Macías
authors: José A
authors: JA
authors: Mira
authors: Manuel
authors: M
authors: Parra-Sánchez
authors: Antonio
authors: A
authors: Rivero-Juárez
authors: Carmen
authors: C
authors: Almeida
authors: Juan A
authors: JA
authors: Pineda
authors: Karin
authors: K
authors: Neukam
mesh_terms: D000328:Adult; D016009:Chi-Square Distribution; D060085:Coinfection; D003430:Cross-Sectional Studies; D054459:Elasticity Imaging Techniques; D005234:Fatty Liver / Q000000981:diagnostic imaging* / Q000821:virology; D005260:Female; D015658:HIV Infections / Q000150:complications / Q000821:virology; D006526:Hepatitis C / Q000150:complications / Q000821:virology; D006801:Humans; D008099:Liver / Q000000981:diagnostic imaging* / Q000821:virology; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D015588:Observer Variation; D011237:Predictive Value of Tests; D011446:Prospective Studies; D015203:Reproducibility of Results