title: Learning curve and intra/interobserver agreement of transient elastography in chronic hepatitis C patients with or without HIV co-infection.
abstract: OBJECTIVE
  Liver stiffness measurement (LSM) by transient elastography has been validated as a noninvasive method to stage liver fibrosis. Few studies have evaluated the learning curve of this method and its reproducibility has led to controversy results. We aimed to evaluate the intra- and interobserver agreement of transient elastography as well as its learning curve for definition of an experimented operator.
  
  
  METHODS
  We retrospectively analyzed 922 examinations performed in 544 patients during a training program of transient elastography. Patients with chronic hepatitis C with or without HIV co-infection that had two examinations by the training operator (intraobserver analysis; n=125) or examination by both training and experimented operators (interobserver analysis; n=151) in the same day were included. LSM was converted to METAVIR score: <7.1 as F0F1, 7.1-9.4 as F2, 9.5-12.4, as F3 and >12.4 kPa as F4.
  
  
  RESULTS
  The overall intra- and interobserver intraclass correlation coefficient [ICC 95% CI] were 0.926 (0.901-0.951) and 0.912 (0.885-0.939), respectively. Measurements were correlated [Spearman's] in intra- [0.906, P<0.0001] and interobserver [0.907, P<0.0001] analysis. Reliability values [kappa (SE)] were k=0.74 (0.09) and k=0.85 (0.08) for fibrosis stages F ≥ 2 and k=0.77 (0.09) and k=0.75 (0.08) for cirrhosis in intra- and interobserver analysis, respectively. Agreement was improved when operator's experience was higher than 100 exams. However, it was observed discordance for fibrosis staging between examinations in a quarter of patients.
  
  
  CONCLUSIONS
  Although there was a considerable discrepancy on fibrosis staging between examinations and a small power, transient elastography had an acceptable reproducibility in our population. Performance of at least 100 examinations should be used to define an experimented operator.
authors.affiliation: National Institute of Infectious Disease - Fundação Oswaldo Cruz, Laboratory of clinical research on STD/AIDS, Rio de Janeiro, Brazil. Electronic address: hugo.perazzo@ini.fiocruz.br.
authors.forename: Hugo
authors.initials: H
authors.lastname: Perazzo
authors.affiliation: Bonsucesso Federal Hospital, Gastroenterology Department, Rio de Janeiro, Brazil.
authors.forename: Flavia F
authors.initials: FF
authors.lastname: Fernandes
authors.affiliation: National Institute of Infectious Disease - Fundação Oswaldo Cruz, Laboratory of clinical research on STD/AIDS, Rio de Janeiro, Brazil.
authors.forename: João Carlos
authors.initials: JC
authors.lastname: Soares
authors.affiliation: National Institute of Infectious Disease - Fundação Oswaldo Cruz, Laboratory of clinical research on STD/AIDS, Rio de Janeiro, Brazil.
authors.forename: Juliana
authors.initials: J
authors.lastname: Fittipaldi
authors.affiliation: National Institute of Infectious Disease - Fundação Oswaldo Cruz, Laboratory of clinical research on STD/AIDS, Rio de Janeiro, Brazil.
authors.forename: Sandra W
authors.initials: SW
authors.lastname: Cardoso
authors.affiliation: National Institute of Infectious Disease - Fundação Oswaldo Cruz, Laboratory of clinical research on STD/AIDS, Rio de Janeiro, Brazil.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Grinsztejn
authors.affiliation: National Institute of Infectious Disease - Fundação Oswaldo Cruz, Laboratory of clinical research on STD/AIDS, Rio de Janeiro, Brazil.
authors.forename: Valdiléa G
authors.initials: VG
authors.lastname: Veloso
mesh_terms: D060085:Coinfection; D003430:Cross-Sectional Studies; D054459:Elasticity Imaging Techniques; D005260:Female; D015658:HIV Infections / Q000150:complications*; D019698:Hepatitis C, Chronic / Q000150:complications* / Q000000981:diagnostic imaging*; D006801:Humans; D059032:Learning Curve; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D012189:Retrospective Studies