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

Figure 1 Effects of age and calendar year on the number of patients presenting with perforated peptic ulcer. Data are Poisson regression with fractional polynomials. 95% confidence intervals are shaded grey, and the y-axis is a logarithmic scale. Left, males. The effect of age was linear in both males and females, without an upper limit. Incidence increased, peaking 10 yr earlier in males than in females.