A prospective comparative study of clinical and histological characteristics in Icelandic and Danish patients with gastric ulcer, duodenal ulcer, and X-ray negative dyspepsia. I. Design and clinical features.

Iceland (IS) and Denmark (DK) are ethnically, culturally, and economically closely related Nordic countries, but gastric cancer is much more frequent in Iceland, and other differences in the occurrence rates of gastric diseases are also suspected. Therefore a cooperative study was initiated comparing Icelandic and Danish patients with gastric ulcer (GU), duodenal ulcer (DU), and X-ray negative dyspepsia (XND) as regards clinical features, external factors of possible importance for gastritis and cancer, gastroscopic appearance, and histological gastric mucosal changes. The project lasted one year and comprised 93 Icelandic and 88 Danish patients. A large number of comparisons showed a high degree of similarity between Icelandic and Danish patients. Significant differences were found in tobacco consumption (DK greater than IS), duration of symptoms in XND (IS greater than DK), whereas the positon ratio of GU (IS less than DK) and acetylsalicylic acid consumption (DK greater than IS) showed non-significant trends. Significant difference was found between the occurrence of diffuse macroscopic changes of the gastric mucosa (IS greater than DK), which corresponds to the histological differences to be described in a subsequent article.