title: Association between beta-interferon exposure and hospital events in multiple sclerosis.
abstract: OBJECTIVE
  A systematic evaluation of hospital events can be an important surrogate measure for drug effectiveness or adverse effects. The purpose of this study was to examine the association between beta-interferon use and hospital events in a large cohort of patients with multiple sclerosis (MS).
  
  
  METHODS
  Retrospective cohort study comparing beta-interferon exposed and unexposed patients using clinical data from the British Columbia MS (BCMS) database linked with health administrative databases, 1996-2008. For each patient, the primary outcome was the number of hospital events in each month, analyzed by quasi Poisson regression. Beta-interferon exposure was examined two ways: current and cumulative exposure. Secondary outcomes included whether a hospital event occurred in each month for each specific primary diagnoses, grouped by International Classification of Diseases categories.
  
  
  RESULTS
  Current exposure to beta-interferon was not associated with an altered rate of hospital events (adjusted incident rate ratio 1.018; 95% CI 0.803-1.290). Similarly, there was no association with cumulative exposure. Cumulative beta-interferon exposure was associated with a lower odds of respiratory disease-related hospital events compared to those never exposed to beta-interferon.
  
  
  CONCLUSIONS
  Exposure to beta-interferon for MS was not associated with a change in overall hospital event rates. Preliminary evidence suggests that the beta-interferons may have a protective effect against respiratory diseases requiring hospitalization in MS patients.
authors: College of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, SK, Canada.
authors: Charity
authors: C
authors: Evans
authors: Feng
authors: F
authors: Zhu
authors: Elaine
authors: E
authors: Kingwell
authors: Afsaneh
authors: A
authors: Shirani
authors: Mia L
authors: ML
authors: van der Kop
authors: John
authors: J
authors: Petkau
authors: Paul
authors: P
authors: Gustafson
authors: Yinshan
authors: Y
authors: Zhao
authors: Joel
authors: J
authors: Oger
authors: Helen
authors: H
authors: Tremlett
mesh_terms: D000328:Adult; D001955:British Columbia / Q000453:epidemiology; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D016899:Interferon-beta / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000188:drug therapy*; D012189:Retrospective Studies
chemical_list: D016899:Interferon-beta
keywords: beta-interferon; hospitalization; multiple sclerosis; pharmacoepidemiology