Epidemiology of perforating peptic ulcer: A population-based retrospective study over 40 years

Figure 2 Effect of calendar year on the number of patients presenting with perforated gastric ulcer (left) and duodenal ulcer (right). Data were Poisson regression with fractional polynomials. 95% confidence intervals are shaded grey, and the y-axis is a logarithmic scale. The incidence of gastric ulcer perforations peaked around 1984, whereas the peak of duodenal ulcer perforations was approximately 15 yr later.