Abstract

Aims: The present analysis served to address the question at what age environmental factors start to exert their influence on the occurrence of ulcerative colitis.

Methods: Mortality data from 21 different countries were accumulated between 1941 and 2004 to analyse the variation of age-specific death rates during consecutive time periods and among different countries.

Results: Between 1941 and 2004 the trends of mortality from ulcerative colitis among different age groups formed a fan-like pattern with a progressively steeper decline of mortality among increasingly younger age groups. This general pattern included mortality in all age groups older than 5 years, but was absent in the youngest age group, 0–4 years. In countries with frequent occurrence of ulcerative colitis, high mortality from ulcerative colitis affected different age groups alike. This pattern was reflected by a set of statistically significant correlations between the mortality of each two consecutive age groups from different countries. The progression of significant correlations among consecutive age groups broke off only when the geographic variations of the age groups 0–4 and 5–9 years were compared.

Conclusions: The analysis suggests that environmental factors responsible for the temporal and geographic variations of ulcerative colitis start to exert their influence during early childhood.