Gastritis staging: interobserver agreement by applying OLGA and OLGIM systems.

Atrophic gastritis remains a difficult histopathological diagnosis with low interobserver agreement. The aim of our study was to compare gastritis staging and interobserver agreement between general and expert gastrointestinal (GI) pathologists using Operative Link for Gastritis Assessment (OLGA) and Operative Link on Gastric Intestinal Metaplasia (OLGIM). We enrolled 835 patients undergoing upper endoscopy in the study. Two general and two expert gastrointestinal pathologists graded biopsy specimens according to the Sydney classification, and the stage of gastritis was assessed by OLGA and OLGIM system. Using OLGA, 280 (33.4 %) patients had gastritis (stage I-IV), whereas with OLGIM this was 167 (19.9 %). OLGA stage III- IV gastritis was observed in 25 patients, whereas by OLGIM stage III-IV was found in 23 patients. Interobserver agreement between expert GI pathologists for atrophy in the antrum, incisura angularis, and corpus was moderate (kappa = 0.53, 0.57 and 0.41, respectively, p < 0.0001), but almost perfect for intestinal metaplasia (kappa = 0.82, 0.80 and 0.81, respectively, p < 0.0001). However, interobserver agreement between general pathologists was poor for atrophy, but moderate for intestinal metaplasia. OLGIM staging provided the highest interobserver agreement, but a substantial proportion of potentially high-risk individuals would be missed if only OLGIM staging is applied. Therefore, we recommend to use a combination of OLGA and OLGIM for staging of chronic gastritis.