title: Pitfalls of liver stiffness measurement: a 5-year prospective study of 13,369 examinations.
abstract: Liver stiffness measurement (LSM) based on transient elastography (TE, FibroScan) is gaining in popularity for noninvasive assessment of liver fibrosis. However, LSM has limitations, which have not yet been thoroughly evaluated. We prospectively investigated the frequency and determinants of LSM failure and unreliable results over a 5-year period, based on 13,369 examinations (134,239 shots). LSM failure was defined as zero valid shots, and unreliable examinations were defined as fewer than 10 valid shots, an interquartile range (IQR)/LSM greater than 30%, or a success rate less than 60%. LSM failure occurred in 3.1% of all examinations (4% at first examination [n = 7261]) and was independently associated at first examination with body mass index (BMI) greater than 30 kg/m(2) (odds ratio [OR], 7.5; 95% confidence interval [CI], 5.6-10.2; P = 0.0001), operator experience fewer than 500 examinations (OR 2.5 [1.6-4.0]; P = 0.0001); age greater than 52 years (OR 2.3 [1.6-3.2]; P = 0.0001), and type 2 diabetes (OR 1.6 [1.1-2.2]; P = 0.009). Unreliable results were obtained in a further 15.8% of cases (17% at first examination) and were independently associated at first examination with BMI greater than 30 kg/m(2) (OR 3.3 [2.8-4.0]; P = 0.0001), operator experience fewer than 500 examinations (OR 3.1 [2.4-3.9]; P = 0.0001), age greater than 52 years (OR 1.8 [1.6-2.1]; P = 0.0001), female sex (OR 1.4 [1.2-1.6], P = 0.0001), hypertension (OR 1.3 [1.1-1.5]; P = 0.003), and type 2 diabetes (OR 1.2 [1.0-1.5]; P = 0.05). When metabolic syndrome and waist circumference were taken into account in a subgroup of 2835 patients, waist circumference was the most important determinant of LSM failure and unreliable results.
  
  
  CONCLUSIONS
  In our experience, liver stiffness measurements are uninterpretable in nearly one in five cases. The principal reasons are obesity, particularly increased waist circumference, and limited operator experience. These results emphasize the need for adequate operator training and for technological improvements in specific patient subpopulations.
authors.affiliation: Services d'Hépato-gastroentérologie, Centre Hospitalo-Universitaire de Bordeaux, Hôpital Haut Lévêque, Avenue Magellan, 33604 Pessac, France. laurent.castera@chu-bordeaux.fr
authors.forename: Laurent
authors.initials: L
authors.lastname: Castéra
authors.forename: Juliette
authors.initials: J
authors.lastname: Foucher
authors.forename: Pierre-Henri
authors.initials: PH
authors.lastname: Bernard
authors.forename: Françoise
authors.initials: F
authors.lastname: Carvalho
authors.forename: Daniele
authors.initials: D
authors.lastname: Allaix
authors.forename: Wassil
authors.initials: W
authors.lastname: Merrouche
authors.forename: Patrice
authors.initials: P
authors.lastname: Couzigou
authors.forename: Victor
authors.initials: V
authors.lastname: de Lédinghen
mesh_terms: D054459:Elasticity Imaging Techniques / Q000592:standards / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D008099:Liver / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D015203:Reproducibility of Results; D013997:Time Factors