Peptic ulcer among Japanese and Koreans in Japan has rarely been studied. In this 10-year study of hospital-based endoscopy, we focused on the epidemiology of peptic ulcer among these ethnic groups in Japan. Between 1980 and 1990, 81.2% of all patients examined via endoscopy at Saikyo Hospital in Kyoto completed a life-style questionnaire: 1,264 Japanese (70.5%), 503 Koreans (28.1%), and 25 persons of unknown ethnicity (1.4%). Characteristics of ulcer disease were almost identical for Koreans and Japanese. Like other worldwide patterns, the male to female ratio was 2.3: 1. Unlike results from Western countries, however, the overall gastric ulcer rate was 1.5 times higher than for duodenal ulcer. This higher rate was due to the relatively high rate of gastric ulcer in the older age groups; among persons <40 years of age, duodenal ulcer was diagnosed more often than gastric ulcer. The mean age at diagnosis of duodenal ulcer (40.7 years) was significantly lower (p < 0.005) than that for gastric ulcer (53.7 years). Multivariate-adjusted odds ratios were calculated using a multiple logistic regression model. Cigarette smoking significantly increased the risk for both gastric ulcer (odds ratio = 3.10, 95% confidence interval [CI] 2.1-4.6) and duodenal ulcer (odds ratio = 1.9, 95% CI 1.2-2.9). Age greater-than-or-equal-to 40 years (odds ratio = 2.3, 95% CI 1.6-3.3) and consumption of salty foods (odds ratio = 1.5, 95% CI 1.0-2.1) also significantly increased the risk for gastric ulcer. Male gender (odds ratio = 2.3, 95% CI 1.5-3.5) and age <40 years (odds ratio = 2.0, 95% CI 1.4-2.9) also significantly increased the risk for duodenal ulcer.
