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 sub-optimal 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 histopathological 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 (US) and Europe. Methods In the 1st phase of the study, 3 pathologists held a consensus conference at which they discussed the diagnostic criteria for LGD. In the 2nd 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 US and 3 from Europe), and interpreted in a blinded fashion. Kappa values were calculated for inter-observer agreement. We performed multinomial logistic regression analysis to assess the weighing of histological features with the diagnosis. Results The overall kappa value for diagnosis was 0.43 (95% CI, 0.42–0.48). When categorized based on degree of dysplasia, the kappa value for non-dysplastic BE was 0.22 (95% CI, 0.11–0.29), for LGD was 0.11 (95% CI, 0.004–0.15), and for high-grade dysplasia was 0.43 (95% CI, 0.36–0.46). When all pathologists made a diagnosis with high confidence, the inter-observer agreement was substantial among US (kappa value of 0.63; 95% CI, 0.61–0.66) and European (kappa value of 0.80; 95% CI, 0.74–0.97) pathologists. The kappa values for all diagnoses made by European pathologists were higher than those made by US-based 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.