Temporal trends and geographical variations of peptic ulcer disease.

The present review describes the time trends and geographical variations of peptic ulcer disease. The study of the epidemiology of peptic ulcer is a worthwhile scientific endeavour, because it provides the necessary background against which hypotheses about the aetiology of the disease can be tested. For individual subjects, the risk of developing peptic ulcer depends upon their date of birth. The risk of developing peptic ulcer has risen in generations, i.e. birth-cohorts, born before the turn of the century, and declined in all subsequent generations. The birth-cohorts with the highest risk of developing gastric ulcer were born 10-20 years before those with the highest risk for duodenal ulcer. The birth-cohort pattern of peptic ulcer disease is found to be similar in all European countries, the USA, Australia and Japan. In gastric ulcer, the birth-related risk involves all ages over 5 years, while in duodenal ulcer it does not start before the age of 15 years. Gastric and duodenal ulcer are both characterized by marked geographical variations that are similar for both types. The similarity in geographical variation is shared by both sexes and all age groups older than 5 or 15 years in case of gastric and duodenal ulcer, respectively. The existence of a birth-cohort phenomenon implies that exogenous risk factors are responsible for the occurrence of peptic ulcer and that subjects are exposed to these risk factors during a limited period of their childhood or early adulthood. As the amount of exposure changes over time, consecutive generations come to reflect the varying amounts of exposure and risk for developing the disease.(ABSTRACT TRUNCATED AT 250 WORDS)