Highlights from this issue

IBD among US Women: a north versus south divide

Geographical variation according to latitude of residence in the incidence of Crohn's disease (CD) and ulcerative colitis (UC) has been reported in Europe with higher rates for northern countries. There are no comparable data for US and no clear data in relation to risk of CD or UC using time points with more plausible biological latency. Khalili et al provide data based on a geographically diverse population of women enrolled in two large prospective studies in the USA: the Nurses’ Health Study I (NHS) in 1976 and the NHS II in 1989. Information on state of residence at the time of birth, at age 15 years and age 30 years was collected in 1992 in NHS I and in 1993 in NHS II. Reported diagnoses of incident CD or UC to the end of 2003 were confirmed by medical record review. The incidence of CD and UC increased significantly with increasing latitude (p trend <0.01), with residence at age 30 years more strongly associated with risk. Compared with women residing in northern latitudes at age 30, the multivariate adjusted HR for women residing in southern latitudes was 0.48 (95% CI 0.30 to 0.77) for CD and 0.62 (95% CI 0.42 to 0.90) for …