ORIGINAL ARTICLE Interobserver reproducibility of the controlled attenuation parameter (CAP) for quantifying liver steatosis Giovanna Ferraioli • Carmine Tinelli • Raffaella Lissandrin • Mabel Zicchetti • Mariangela Rondanelli • Guido Perani • Stefano Bernuzzi • Laura Salvaneschi • Carlo Filice Received: 20 February 2014 / Accepted: 15 August 2014 / Published online: 20 September 2014 Ó Asian Pacific Association for the Study of the Liver 2014 Abstract Purpose This study was conducted to prospectively investigate the interobserver reproducibility of controlled attenuation parameter (CAP) measurements and the rela- tionship among the CAP and body mass index (BMI), gender and age. Methods Consecutive subjects were studied using the M? probe of the FibroScan device (Echosens, Paris, France). Measurements were performed by two raters (rater1 and rater2). Interobserver agreement was assessed by using the concordance correlation coefficient (CCC). The Pearson r coefficient was used to test correlation between two study variables, and linear regression was used for the multivariate model. Results Three hundred fifty-one subjects (227 males and 124 females) were prospectively studied. The CCC was 0.82 (95 % CI 0.78–0.85) overall, 0.80 (95 % CI 0.75–0.85) for BMI \25 kg/m 2 , 0.76 (95 % CI 0.69–0.84) for BMI 25–29 kg/m 2 and 0.65 (95 % CI 0.41–0.88) for BMI C30 kg/m 2 . The CCC was 0.44 (95 % CI 0.31–0.56) for CAP values B240 dB/m and 0.72 (95 % CI 0.65–0.79) for CAP values [240 dB/m. In univariate analysis, age and BMI by gender were correlated with the CAP. Multiple regression analysis confirmed the relationship of the CAP with age and BMI, but not with gender. Conclusions The results of this study show that the in- terreader agreement in CAP measurement is good. In healthy volunteers, the CAP is strongly correlated with age and BMI. Keywords Liver steatosis Á Noninvasive techniques Á Controlled attenuation parameter Á Transient elastography Á Reproducibility studies Á Interobserver agreement On behalf of the Liver Steatosis Study Group. Liver Steatosis Study Group Elisabetta Above, MD, Giorgio Barbarini, MD, Raffaele Bruno, MD, Silvia Corona, MSc, Carolina Dellafiore, MD, Marta Di Gregorio, MD, Roberto Gulminetti, MD, Paolo Lanzarini, MD, Serena Ludovisi, MD, Laura Maiocchi, MD, Antonello Malfitano, MD, Giuseppe Michelone, MD, Lorenzo Minoli, MD, Mario Mondelli, MD, Stefano Novati, MD, Savino F.A. Patruno, MD, Alessandro Perretti, MD, Gianluigi Poma, MD, Paolo Sacchi, MD, Domenico Zanaboni, MD, and Marco Zaramella, MD. G. Ferraioli (&) Á R. Lissandrin Á M. Zicchetti Á C. Filice Ultrasound Unit, Department of Infectious Diseases, Fondazione IRCCS Policlinico San Matteo, University of Pavia, Via Taramelli 5, 27100 Pavia, Italy e-mail: giovanna.ferraioli@unipv.it C. Tinelli Clinical Epidemiology and Biometric Unit, Fondazione IRCCS Policlinico San Matteo, Viale Camillo Golgi 19, 27100 Pavia, Italy M. Rondanelli Department of Applied Health Sciences, Istituto di Cura ‘‘Santa Margherita’’, University of Pavia, Via Emilia 12, 27100 Pavia, Italy G. Perani Department of Internal Medicine, Fondazione IRCCS Policlinico San Matteo, Viale Camillo Golgi 19, 27100 Pavia, Italy S. Bernuzzi Á L. Salvaneschi Department of ‘‘Medicina Diagnostica e dei Servizi’’, Fondazione IRCCS Policlinico San Matteo, Viale Camillo Golgi 19, 27100 Pavia, Italy 123 Hepatol Int (2014) 8:576–581 DOI 10.1007/s12072-014-9573-1