title: Long-term clinical outcomes of urban versus rural environment in Korean patients with Crohn's disease: results from the CONNECT study.
abstract: OBJECTIVE
  Environmental factors and genetic predisposition are thought to play important roles in the pathogenesis of Crohn's disease [CD]. Although numerous studies have reported the positive association between urban environment and CD development, few studies have compared the clinical outcomes between urban and rural environments. Therefore, this study aimed to compare the clinical characteristics and long-term prognosis between urban and rural populations of patients with CD.
  
  
  METHODS
  This retrospective multicenter cohort study included 1002 Korean patients diagnosed with CD [743 urban residents and 259 rural residents] between 1982 and 2008 from 32 medical centers. The clinical outcomes of urban versus rural populations were compared using the KaplanMeier method and log-rank test.
  
  
  RESULTS
  Disease distribution and behavior of the urban population did not differ from those of the rural population. There were no significant differences in the cumulative probabilities of perianal fistula [P = 0.086] and intestinal complications such as stricture [P = 0.109], fistula [P = 0.952], abscess [P = 0.227], and perforation [P = 0.382] between the two groups. In addition, no significant differences were observed between the two groups with regard to the cumulative probabilities of immunosuppressant use [P = 0.527] and biologic agent use [P = 0.731]. Although the cumulative probability of surgery in the urban population was significantly higher than that in the rural population [P = 0.040], this difference was mainly established within the first year from diagnosis [19.1% vs 13.5%, P = 0.042] and observed only among patients diagnosed in 2005-2008 [P = 0.033].
  
  
  CONCLUSIONS
  There were no differences in terms of disease presentation and natural history between urban and rural populations, except for a higher rate of surgery in the urban population who were recently diagnosed with CD.
authors.affiliation: Department of Internal Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Yoon Suk
authors.initials: YS
authors.lastname: Jung
authors.affiliation: Department of Internal Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea diksmc.park@samsung.com.
authors.forename: Dong Il
authors.initials: DI
authors.lastname: Park
authors.affiliation: Department of Gastroenterology and Inflammatory Bowel Disease Center, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Byong Duk
authors.initials: BD
authors.lastname: Ye
authors.affiliation: Department of Internal Medicine and Institute of Gastroenterology, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Jae Hee
authors.initials: JH
authors.lastname: Cheon
authors.affiliation: Department of Internal Medicine, Seoul Paik Hospital, Inje University College of Medicine, Seoul, Korea.
authors.forename: You Sun
authors.initials: YS
authors.lastname: Kim
authors.affiliation: Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Young Ho
authors.initials: YH
authors.lastname: Kim
authors.affiliation: Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Joo Sung
authors.initials: JS
authors.lastname: Kim
authors.affiliation: Department of Internal Medicine, Uijeongbu St Mary's Hospital, College of Medicine, Catholic University of Korea, Uijeongbu, Korea.
authors.forename: Hiun Suk
authors.initials: HS
authors.lastname: Chae
authors.affiliation: Department of Internal Medicine, ChunCheon Sacred Heart Hospital, Hallym University College of Medicine, Chuncheon-si, Korea.
authors.forename: Gwang Ho
authors.initials: GH
authors.lastname: Baik
authors.affiliation: Department of Internal Medicine, Hanyang University College of Medicine, Guri, Korea.
authors.forename: Dong Soo
authors.initials: DS
authors.lastname: Han
mesh_terms: D000328:Adult; D003424:Crohn Disease / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology / Q000628:therapy; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D016015:Logistic Models; D008297:Male; D011379:Prognosis; D056910:Republic of Korea; D012189:Retrospective Studies; D012423:Rural Health; D014504:Urban Health
keywords: Crohn’s disease; clinical outcome; rural environment; urban environment