title: An inter-observer agreement study of autofluorescence endoscopy in Barrett's esophagus among expert and non-expert endoscopists.
abstract: BACKGROUND
  Autofluorescence imaging (AFI), which is a "red flag" technique during Barrett's surveillance, is associated with significant false positive results. The aim of this study was to assess the inter-observer agreement (IOA) in identifying AFI-positive lesions and to assess the overall accuracy of AFI.
  
  
  METHODS
  Anonymized AFI and high resolution white light (HRE) images were prospectively collected. The AFI images were presented in random order, followed by corresponding AFI + HRE images. Three AFI experts and 3 AFI non-experts scored images after a training presentation. The IOA was calculated using kappa and accuracy was calculated with histology as gold standard.
  
  
  RESULTS
  Seventy-four sets of images were prospectively collected from 63 patients (48 males, mean age 69 years). The IOA for number of AF positive lesions was fair when AFI images were presented. This improved to moderate with corresponding AFI and HRE images [experts 0.57 (0.44-0.70), non-experts 0.47 (0.35-0.62)]. The IOA for the site of AF lesion was moderate for experts and fair for non-experts using AF images, which improved to substantial for experts [κ = 0.62 (0.50-0.72)] but remained at fair for non-experts [κ = 0.28 (0.18-0.37)] with AFI + HRE. Among experts, the accuracy of identifying dysplasia was 0.76 (0.7-0.81) using AFI images and 0.85 (0.79-0.89) using AFI + HRE images. The accuracy was 0.69 (0.62-0.74) with AFI images alone and 0.75 (0.70-0.80) using AFI + HRE among non-experts.
  
  
  CONCLUSIONS
  The IOA for AF positive lesions is fair to moderate using AFI images which improved with addition of HRE. The overall accuracy of identifying dysplasia was modest, and was better when AFI and HRE images were combined.
authors.affiliation: Nottingham Digestive Diseases Centre and NIHR Biomedical Research Unit, Queens Medical Centre Campus, Nottingham University Hospitals NHS Trust, Nottingham, NG7 2UH, UK.
authors.forename: J
authors.initials: J
authors.lastname: Mannath
authors.forename: V
authors.initials: V
authors.lastname: Subramanian
authors.forename: E
authors.initials: E
authors.lastname: Telakis
authors.forename: K
authors.initials: K
authors.lastname: Lau
authors.forename: V
authors.initials: V
authors.lastname: Ramappa
authors.forename: M
authors.initials: M
authors.lastname: Wireko
authors.forename: P V
authors.initials: PV
authors.lastname: Kaye
authors.forename: K
authors.initials: K
authors.lastname: Ragunath
mesh_terms: D000368:Aged; D001471:Barrett Esophagus / Q000175:diagnosis*; D016145:Endoscopy, Digestive System / Q000379:methods / Q000592:standards* / Q000706:statistics & numerical data; D005260:Female; D005762:Gastroenterology / Q000592:standards*; D006801:Humans; D008297:Male; D015588:Observer Variation; D061848:Optical Imaging / Q000379:methods / Q000592:standards* / Q000706:statistics & numerical data; D011230:Precancerous Conditions / Q000175:diagnosis*; D011446:Prospective Studies; D012015:Reference Standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity