4 WORLD GASTROENTEROLOGY NEWS APRIL 2015 Editorial | Expert Point of View | Gastro 2015: AGW/WGO | WDHD News | WGO & WGOF News | WGO Global Guidelines | Calendar of Events Migratory Movements and the Risk of Inflammatory Bowel Disease Manuel Barreiro-de Acosta, MD, PhD Department of Gastroenterology and Hepatology University Hospital of Santiago de Compostela Santiago de Compostela, Spain J. Enrique Domínguez-Muñoz, MD Department of Gastroenterology and Hepatology University Hospital of Santiago de Compostela Santiago de Compostela, Spain All around the world, the incidence and prevalence of inflammatory bowel disease (IBD) have been changing over the last several decades. While there has typically been a North-South gradient in the distribution of IBD with the incidence of IBD being higher in the more developed North countries, the prevalence of these diseases has markedly increased in South countries over the last years which changes the North South gradient The etiology of Crohn’s disease (CD) and ulcerative colitis (UC) is largely unknown, but environmental factors are widely accepted to play a relevant etiopathogenic role. In fact, industrialization and high socioeconomic status are well known risk factors for IBD. A recent case-control study with a significant number of IBD patients showed that air pollution exposure was not associated with the incidence of IBD, but that residential exposure to SO2 and NO2 may increase the risk of early-onset UC and CD, respectively 1. Population migratory movements have existed for centuries, but recent changes such as globalization, deep- ening socioeconomical differences among countries, significant increases in the number and frequency of longdistance travels, and increased ease of moving from one country to another have helped to increase the migration of people around the globe. In addition, migratory movements can now be more easily measured and evaluated. Since human migration tend to follow the rule of moving from developing to developed countries, and thus from countries with a low prevalence of IBD to those with a high prevalence of IBD, the question arises of how migratory movements do modify the risk of IBD. The first data about the impact of migration on IBD came from British studies of migrants from Asia to Europe. In a study of Bangladeshi immigrants who settled in East London, CD rates were significantly higher in Bangladeshis under 20 years of age compared with relatives who remained in Bangladesh 2. In another British study of UC patients, authors showed that second generation South-Asian immigrants had a higher risk of being diagnosed with UC than first generation immigrants 3. Figures for second generation South-Asian immigrants were similar to those of the UK Caucasian population, thus supporting the significant role of environmental factors in the etiopathogenesis of IBD. Similar data have been reported on Hispanic migrants to the USA (Miami, Florida) 4. In that study, the age of IBD diagnosis in the second generation Hispanics, who were born in USA, was lower than in those people who were born in their original Hispanic country. A pediatric population is probably the most appropriate group for evaluating all of these epidemiological changes. In a Canadian study, authors observed that the diagnosis of IBD in second generation South Asian children was higher than in the Caucasian population, confirming the results previously shown 5. In our population of the North- West of Spain, we evaluated the influence of migratory movements in IBD diagnosis in a prospective case-control study 6. This was especially interesting since people from North-West Spain who migrated decades ago after the Spanish civil war (1936-1939), mainly to Western European and Latin American countries, moved recently back to their original towns. We hypothesized that people who migrated to more industrialized countries than Spain would have a higher risk of developing IBD than those migrating to less industrialized countries or to those remaining in Spain. A total of 242 patients diagnosed with IBD over the last 10 years were evaluated together with the same number of healthy, unrelated controls matched by ethnicity, sex, age and smoking habits, family size and study levels, and with
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