[Clinical Application of the Kyoto Classification of Gastritis]

Recent advances in endoscopic technology, including high-definition and image-enhanced endoscopy such as narrow-band imaging have facilitated close observation and detailed imaging of the gastric mucosa. Currently, endoscopy is performed in Korea primarily for evaluation of premalignant conditions and gastric cancer detection. Recent research has established the Kyoto classification of gastritis, a novel grading system for endoscopic gastritis, which enables prediction of Helicobacter pylori (H. pylori) infection. The Kyoto classification score is calculated based on the sum of scores for five main items (of 19 endoscopic findings indicative of H. pylori infection) such as atrophy, intestinal metaplasia, enlarged gastric folds, nodularity, and diffuse redness with/without regular arrangement of collecting venules (RAC). Of these five endoscopic findings, atrophy, intestinal metaplasia, enlarged gastric folds, and nodularity are associated with an increased risk and RAC with a decreased risk of gastric cancer. Previous studies have reported that a Kyoto classification score ≥2 indicates current or past H. pylori infection. An increase in the Kyoto classification score is associated with a high risk of gastric cancer; specifically, a Kyoto classification score ≥4 indicates a high risk of gastric cancer. However, H. pylori eradication is followed by disappearance of enlarged gastric folds, nodularity, and diffuse redness; therefore, this grading system cannot accurately reflect the gastric cancer risk in patients with previous H. pylori infection. Limited studies have discussed the Kyoto classification of gastritis in Korea. Therefore, further large-scale multicenter studies are warranted for validation of the Kyoto classification to predict H. pylori infection and gastric cancer risk.