Age of inflammatory bowel diseases (IBD) onset varies with sex, according to a recent pooled analysis of population-based studies from western countries. Researchers identified population-based cohorts of patients for IBD for which incidence and age data were available. Data were collected through December 2016 on 95,605 incident cases of Crohn’s disease (CD) and 112,004 incident cases of ulcerative colitis (UC). Incidence rate ratios of CD and UC were pooled for the combined cohort and differences compared according to sex using random-effects meta-analysis. Among the findings:

• Female patients had a lower risk of CD during childhood (aged 10-14 years), but had a higher risk of CD thereafter, which was statistically significant for the age groups of 25-29 years and >35 years.
• The incidence of UC did not differ significantly for female vs male patients until age 45 years.
• Men had a significantly higher incidence of UC vs women after age 45 years.