Epidemiology Rate higher in northern climates and the developed world a Equal incidence between men and women ■ Peak incidence CD 15-35 years by far the commonest UC usually diagnosed prior to 30 years Aggregation in families 25%of patients with CD 20 %of patients with UC a Smoking reduces risk of Uc but increases risk of cdEpidemiology  Rate higher in northern climates and the developed world  Equal incidence between men and women  Peak incidence CD 15-35 years by far the commonest UC usually diagnosed prior to 30 years  Aggregation in families 25 % of patients with CD 20 % of patients with UC  Smoking reduces risk of UC but increases risk of CD