title: Upper gastrointestinal tract phenotype of Crohn's disease is associated with early surgery and further hospitalization.
abstract: BACKGROUND
  According to the Montreal Classification, upper gastrointestinal tract phenotype L4 is uncommon in Caucasian patients with Crohn's disease (CD) but carries excess risk of recurrence. We studied the clinical course of CD in Chinese patients presenting with the L4 phenotype and factors predicting its occurrence upon longitudinal follow-up.
  
  
  METHODS
  This prospective cohort study included 132 Chinese CD patients (median age at diagnosis, 30.0 years, range: 14.0-77.0 years) who were followed for 770 person-years. Demographic data including disease behavior and location, details of surgery, and hospitalization were collected. The Kaplan-Meier method was used to estimate the probabilities of further hospitalization and major surgery followed by Cox proportional hazards regression to determine if clinical variables independently predicted the endpoints.
  
  
  RESULTS
  The L4 phenotype was found in 30 (22.7%) patients at presentation. There were significantly more stricturing (46.7% versus 18.6%) and penetrating (30.0% versus 3.9%) phenotypes in the L4 group than in the non-L4 group (P < 0.0001). The 3-year cumulative probability of further hospitalization was 86.9% (95% confidence interval [CI]: 73.8%-100.0%) in the L4 group as compared with 49.3% (95% CI: 39.3%-59.3%) in the non-L4 group (log-rank test, P < 0.0001). The L4 phenotype independently predicted further hospitalization (adjusted hazards ratio [HR]: 2.1; 95% CI: 1.3-3.5). The cumulative probability of major surgery was significantly higher in the L4 than in the non-L4 group (P < 0.0001). Eighteen (17.6%) patients developed the L4 phenotype on follow-up and the stricturing phenotype predicted its occurrence (adjusted HR: 5.5; 95% CI: 2.2-14.0).
  
  
  CONCLUSIONS
  Chinese CD patients more often had the L4 phenotype, which predicted the need of subsequent hospitalization.
authors.affiliation: Institute of Digestive Disease, Chinese University of Hong Kong, Department of Medicine and Therapeutics, Prince of Wales Hospital, Hong Kong. chowkailai@yahoo.com.hk
authors.forename: Dorothy K L
authors.initials: DK
authors.lastname: Chow
authors.forename: Joseph J Y
authors.initials: JJ
authors.lastname: Sung
authors.forename: Justin C Y
authors.initials: JC
authors.lastname: Wu
authors.forename: Kelvin K F
authors.initials: KK
authors.lastname: Tsoi
authors.forename: Rupert W L
authors.initials: RW
authors.lastname: Leong
authors.forename: Francis K L
authors.initials: FK
authors.lastname: Chan
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D044466:Asian People / Q000706:statistics & numerical data*; D003424:Crohn Disease / Q000145:classification / Q000208:ethnology* / Q000601:surgery*; D013505:Digestive System Surgical Procedures / Q000706:statistics & numerical data*; D005260:Female; D005500:Follow-Up Studies; D006723:Hong Kong / Q000453:epidemiology; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010641:Phenotype; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D012307:Risk Factors; D055815:Young Adult