No association between urbanisation, neighbourhood deprivation and IBD: a population-based study of 4 million individuals.

We read with interest the recently published work in Gut by Imhann et al .1 Although this paper suggests that genetics plays an important role in IBD,1 environmental factors clearly contribute to its aetiology.2 When Ng et al 2 reviewed environmental risk factors for IBD in this journal they noted that urbanisation may be linked to both Crohn’s disease (CD) and ulcerative colitis (UC).We used Cox regression to estimate the effect of urbanisation and deprivation during childhood on future IBD.From the Swedish Total Population Register,3 the government agency Statistics Sweden selected all individuals born in Sweden between 1973 and 2013 (n=4 161 280). Among these there …