title: Influence of urban/rural and coastal/inland environment on the prevalence, phenotype, and clinical course of inflammatory bowel disease patients from northwest of Spain: a cross-sectional study.
abstract: BACKGROUND
  Data on the influence of rural/urban and coastal/inland environment on inflammatory bowel disease (IBD) are either conflicting or lacking. Our aim was to analyze whether the environment has any influence on the prevalence, phenotype, and course of IBD.
  
  
  METHODS
  We carried out a multicenter retrospective study in 1194 IBD patients from Galicia, Spain. Urban areas were defined as those with over 25,000 inhabitants. Sex, age, family history, smoking, Montreal classification, extraintestinal manifestations, steroid dependence/refractoriness, and treatment were assessed. We used the Student's t-test/Mann-Whitney U tests to compare continuous variables and χ to compare categorical variables. Logistic regression was also used.
  
  
  RESULTS
  Living in urban municipalities was a risk factor for Crohn's disease [relative risk (RR) 1.47; 95% confidence interval (CI) 1.25-1.73; P<0.001]; living in coastal municipalities was a protective factor for ulcerative colitis (RR 0.71; 95% CI 0.60-0.85; P<0.001). Crohn's disease patients living on the coast had more frequent ileocolonic disease and needed immunosuppressives more frequently than inland patients (RR for inland 0.65; 95% CI 0.47-0.90; P=0.008). Urban Crohn's disease patients needed immunosuppressives more frequently than rural patients (RR 1.41; 95% CI 1.04-1.92; P=0.027). Urban ulcerative colitis patients had left-sided colitis less frequently. Coastal ulcerative colitis patients more frequently had extensive colitis.
  
  
  CONCLUSIONS
  Crohn's disease was found more frequently in urban and coastal areas and ulcerative colitis in inland municipalities. Place of residence may also influence phenotype and clinical course as patients living on the coast have more frequent ileocolonic Crohn's disease phenotype, extensive ulcerative colitis, and greater need for immunosuppressive therapy.
authors.affiliation: aDepartment of Gastroenterology, Complexo Hospitalario Universitario de Pontevedra, Pontevedra bDepartment of Gastroenterology, Complexo Hospitalario Universitario de Santiago de Compostela, Santiago de Compostela cDepartment of Gastroenterology, Hospital Arquitecto Marcide, Ferrol dDepartment of Gastroenterology, Complexo Hospitalario Universitario de Vigo, Vigo, Spain.
authors.forename: Daniel
authors.initials: D
authors.lastname: Carpio
authors.forename: Manuel
authors.initials: M
authors.lastname: Barreiro-de Acosta
authors.forename: Ana
authors.initials: A
authors.lastname: Echarri
authors.forename: Santos
authors.initials: S
authors.lastname: Pereira
authors.forename: Javier
authors.initials: J
authors.lastname: Castro
authors.forename: Rocio
authors.initials: R
authors.lastname: Ferreiro
authors.forename: Aurelio
authors.initials: A
authors.lastname: Lorenzo
mesh_terms: D000328:Adult; D016009:Chi-Square Distribution; D003093:Colitis, Ulcerative / Q000175:diagnosis / Q000453:epidemiology* / Q000628:therapy; D003424:Crohn Disease / Q000175:diagnosis / Q000453:epidemiology* / Q000628:therapy; D003430:Cross-Sectional Studies; D004777:Environment; D005260:Female; D006801:Humans; D007166:Immunosuppressive Agents / Q000627:therapeutic use; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D015995:Prevalence; D011379:Prognosis; D065840:Protective Factors; D012111:Residence Characteristics; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D012423:Rural Health; D012720:Severity of Illness Index; D013030:Spain / Q000453:epidemiology; D014504:Urban Health
chemical_list: D007166:Immunosuppressive Agents