The incidence in Copenhagen County of gastric and duodenal ulcers in the same patient.

This study represents a prospective, epidemiologic study dealing with patients from a geographically well-defined area of Denmark who had both a gastric and a duodenal ulcer diagnosed during the years 1963-1968. The average annual incidence of new cases was 1.6 per 10,000 inhabitants aged 15 years and over, which is a higher incidence than any registered so far, especially compared with the frequencies of solitary gastric and duodenal ulcers. The incidence was 20 times as high as might be expected if the occurrence of the syndrome was incidental only. In both sexes the incidence increased with age in a manner similar to that seen in solitary gastric ulcers. The male:female ratio was 2.2:1. The incidence of cases in which both ulcers appeared simultaneously at the first 'positive' diagnostic examination was 0.7 per 10,000 at risk. Certain observations indicate, however, that even in those cases, the two ulcer components have arisen at different times.