title: The feasibility and reliability of transient elastography using Fibroscan®: a practice audit of 2335 examinations.
abstract: BACKGROUND
  Liver stiffness measurement (LSM) using transient elastography is widely used in the management of patients with chronic liver disease.
  
  
  OBJECTIVE
  To examine the feasibility and reliability of LSM, and to identify patient and operator characteristics predictive of poorly reliable results.
  
  
  METHODS
  The present retrospective study investigated the frequency and determinants of poorly reliable LSM (interquartile range [IQR]⁄median LSM [IQR⁄M] >30% with median liver stiffness ≥7.1 kPa) using the FibroScan (Echosens, France) over a three-year period. Two experienced operators performed all LSMs. Multiple logistic regression analyses examined potential predictors of poorly reliable LSMs including age, sex, liver disease, the operator, operator experience (<500 versus ≥500 scans), FibroScan probe (M versus XL), comorbidities and liver stiffness. In a subset of patients, medical records were reviewed to identify obesity (body mass index ≥30 kg⁄m2).
  
  
  RESULTS
  Between July 2008 and June 2011, 2335 patients with liver disease underwent LSM (86% using the M probe). LSM failure (no valid measurements) occurred in 1.6% (n=37) and was more common using the XL than the M probe (3.4% versus 1.3%; P=0.01). Excluding LSM failures, poorly reliable LSMs were observed in 4.9% (n=113) of patients. Independent predictors of poorly reliable LSM included older age (OR 1.03 [95% CI 1.01 to 1.05]), chronic pulmonary disease (OR 1.58 [95% CI 1.05 to 2.37), coagulopathy (OR 2.22 [95% CI 1.31 to 3.76) and higher liver stiffness (OR per kPa 1.03 [95% CI 1.02 to 1.05]), including presumed cirrhosis (stiffness ≥12.5 kPa; OR 5.24 [95% CI 3.49 to 7.89]). Sex, diabetes, the underlying liver disease and FibroScan probe were not significant. Although reliability varied according to operator (P<0.0005), operator experience was not significant. In a subanalysis including 434 patients with body mass index data, obesity influenced the rate of poorly reliable results (OR 2.93 [95% CI 0.95 to 9.05]; P=0.06).
  
  
  CONCLUSIONS
  FibroScan failure and poorly reliable LSM are uncommon. The most important determinants of poorly reliable results are older age, obesity, higher liver stiffness and the operator, the latter emphasizing the need for adequate training.
authors.forename: Jack X Q
authors.initials: JX
authors.lastname: Pang
authors.forename: Faruq
authors.initials: F
authors.lastname: Pradhan
authors.forename: Scott
authors.initials: S
authors.lastname: Zimmer
authors.forename: Sophia
authors.initials: S
authors.lastname: Niu
authors.forename: Pam
authors.initials: P
authors.lastname: Crotty
authors.forename: Jenna
authors.initials: J
authors.lastname: Tracey
authors.forename: Christopher
authors.initials: C
authors.lastname: Schneider
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Heitman
authors.forename: Gilaad G
authors.initials: GG
authors.lastname: Kaplan
authors.forename: Mark G
authors.initials: MG
authors.lastname: Swain
authors.forename: Robert P
authors.initials: RP
authors.lastname: Myers
mesh_terms: D000328:Adult; D015897:Comorbidity; D054459:Elasticity Imaging Techniques / Q000295:instrumentation / Q000592:standards* / Q000706:statistics & numerical data; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008103:Liver Cirrhosis / Q000000981:diagnostic imaging*; D016015:Logistic Models; D008297:Male; D008485:Medical Audit; D008875:Middle Aged; D009765:Obesity; D012372:ROC Curve; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012720:Severity of Illness Index