Discordance Among Pathologists in the United States and Europe in Diagnosis of Low-Grade Dysplasia for Patients With Barrett's Esophagus.

BACKGROUND & AIMS: There is suboptimal inter-observer agreement, even among expert gastrointestinal pathologists, in the diagnosis of low-grade dysplasia (LGD) in patients with Barrett's esophagus (BE). We analyzed histopathologic criteria required for a diagnosis of LGD using the new subcategories of LGD with inflammatory and dysplastic features. We categorized each diagnosis based on the level of confidence and assessed inter-observer agreement among gastrointestinal pathologists from 5 tertiary centers in the United States and Europe. METHODS: In the first phase of the study, 3 pathologists held a consensus conference at which they discussed the diagnostic criteria for LGD. In the second phase, 79 slides from patients with BE (23 samples of non-dysplastic BE, 22 samples of LGD, and 34 samples of high-grade dysplasia) were identified, randomly assigned to 7 pathologists (4 from the United States and 3 from Europe), and interpreted in a blinded fashion. κ Values were calculated for inter-observer agreement. We performed multinomial logistic regression analysis to assess the weighting of histologic features with the diagnosis. RESULTS: The overall κ value for diagnosis was 0.43 (95% confidence interval [CI], 0.42-0.48). When categorized based on degree of dysplasia, the κ value was 0.22 (95% CI, 0.11-0.29) for non-dysplastic BE, 0.11 (95% CI, 0.004-0.15) for LGD, and 0.43 (95% CI, 0.36-0.46) for high-grade dysplasia. When all pathologists made a diagnosis with high confidence, the inter-observer agreement was substantial among the US pathologists (κ, 0.63; 95% CI, 0.61-0.66) and European pathologists (κ, 0.80; 95% CI, 0.74-0.97). The κ values for all diagnoses made by European pathologists were higher than those made by US pathologists. CONCLUSIONS: In an analysis of criteria used in histopathologic diagnosis of LGD, we did not observe improvement in level of agreement among experienced pathologists, even after accounting for inflammation. The level of inter-observer agreement increased with level of pathologist confidence. There was also a difference in reading of histopathology samples of BE tissues between US and European pathologists.