Objective: A birth-cohort phenomenon in the time trends of a disease indicates that exposure to relevant risk factors must have occurred during an early period of life. The aim of this study was to determine whether birth-cohort patterns are common features of ulcerative colitis, gastric ulcer, and duodenal ulcer in different countries.
Methods: The number of deaths from ulcerative colitis, gastric, and duodenal ulcer in England, Netherlands, Italy, Switzerland, United States, and Scotland were retrieved from the respective national statistics offices. The death rates from the six countries were plotted against the period of birth. Age-standardized cohort mortality ratios were calculated as a summary of the overall mortality associated with each consecutive birth-cohort.
Results: In all countries alike, mortality from ulcerative colitis, gastric, and duodenal ulcer increased among successive generations born during the 19th century and, after reaching a sharp peak around the turn of the 20th century, declined among generations born subsequently. The rise in mortality from gastric ulcer preceded a similar rise in mortality from duodenal ulcer by 10-20 yr, and the temporal changes of duodenal ulcer coincided with those of ulcerative colitis.
Conclusions: The sudden rise of peptic ulcer disease during the 19th century and the 10-20-yr time lag between gastric and duodenal ulcer are difficult to explain based on changing infection rates with Helicobacterpylori alone. The similarity between the time trends of duodenal ulcer and ulcerative colitis suggests the influence of one or more shared risk factors.