The annual age-standardised incidence increased from 3.5 to 18.5 per 100 000 during the study period (P < .01). Correspondingly, the prevalence increased from 44 to 474 per 100 000 between 1965 and 2010. A higher proportion of males than females had extensive colitis at diagnosis (odds ratio: 1.55; 95% CI 1.17-2.05; P < .01). The risk for progression in disease extent was 34.5% and 18.5% at 10 years, for patients with proctitis and left-sided colitis, respectively (P < .01).
