title: Adherence to disease-modifying therapies for multiple sclerosis and subsequent hospitalizations.
abstract: OBJECTIVE
  The aim of this study was to examine the association between optimal adherence to first-line disease-modifying therapies (DMT) for multiple sclerosis (MS) and hospitalizations.
  
  
  METHODS
  We used population-based administrative data from three Canadian provinces. All individuals receiving DMT (interferon-B-1b, interferon-B-1a, or glatiramer acetate) between January 1, 1996, and December 31, 2011 (British Columbia); March 31, 2012 (Manitoba); or March 31, 2014, (Saskatchewan) were included. Adherence was estimated for the first year of DMT (year 0), using the medication possession ratio (MPR). The association between optimal adherence (MPR ≥ 80%) and all-cause and MS-specific hospitalizations in the subsequent 1, 2, and 5 years was assessed using Hurdle Poisson and logistic regression. Rate and odds ratios were adjusted (aRR and aOR) for sociodemographic factors and prior health-care utilization.
  
  
  RESULTS
  Overall, 4746 subjects were followed for a mean 7.8 (SD 4.0) years; 3598 (76%) were women. Optimal DMT adherence was achieved in 3564/4746 (75.1%) subjects. Subsequent all-cause and MS-specific hospitalizations were lower for subjects with optimal versus suboptimal adherence, but none reached statistical significance (1-year period, aRR = 0.77, 95%CI: 0.47-1.26; aOR = 0.80, 95%CI: 0.52-1.25). Similar findings were observed in the 2-year and 5-year periods. Prior health-care utilization (hospitalizations and medications) was associated with future hospitalizations; for every additional medication class, the 5-year all-cause hospitalization rate and likelihood of an MS-specific hospitalization increased by 5% and 11%, respectively (aRR = 1.05, 95%CI: 1.02-1.07; and aOR = 1.11, 95%CI: 1.07-1.14).
  
  
  CONCLUSIONS
  Hospitalization rates were lower in subjects with optimal DMT adherence, but findings were not statistically significant. Prior hospitalization and polypharmacy were associated with increased risk for future hospitalizations in MS. Copyright © 2017 John Wiley & Sons, Ltd.
authors.affiliation: College of Pharmacy & Nutrition, University of Saskatchewan, Saskatoon, SK, Canada.
authors.forename: Charity
authors.identifier: http://orcid.org/0000-0003-1409-0214
authors.initials: C
authors.lastname: Evans
authors.affiliation: Departments of Internal Medicine and Community Health Sciences, University of Manitoba, Winnipeg, MB, Canada.
authors.forename: Ruth Ann
authors.initials: RA
authors.lastname: Marrie
authors.affiliation: Department of Medicine (Neurology), University of British Columbia, Vancouver, BC, Canada.
authors.forename: Feng
authors.initials: F
authors.lastname: Zhu
authors.affiliation: Department of Community Health Sciences, University of Manitoba, Winnipeg, MB, Canada.
authors.forename: Stella
authors.initials: S
authors.lastname: Leung
authors.affiliation: Saskatchewan Health Quality Council, Saskatoon, SK, Canada.
authors.forename: Xinya
authors.initials: X
authors.lastname: Lu
authors.affiliation: Department of Medicine (Neurology), University of British Columbia, Vancouver, BC, Canada.
authors.forename: Elaine
authors.initials: E
authors.lastname: Kingwell
authors.affiliation: Department of Medicine (Neurology), University of British Columbia, Vancouver, BC, Canada.
authors.forename: Yinshan
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Department of Medicine (Neurology), University of British Columbia, Vancouver, BC, Canada.
authors.forename: Helen
authors.initials: H
authors.lastname: Tremlett
mesh_terms: D000328:Adult; D001955:British Columbia / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D000068717:Glatiramer Acetate / Q000627:therapeutic use*; D006760:Hospitalization / Q000639:trends*; D006801:Humans; D007345:Insurance Claim Review / Q000639:trends; D016899:Interferon-beta / Q000627:therapeutic use*; D008297:Male; D008350:Manitoba / Q000453:epidemiology; D055118:Medication Adherence; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000188:drug therapy* / Q000453:epidemiology*; D011159:Population Surveillance / Q000379:methods; D012189:Retrospective Studies; D012525:Saskatchewan / Q000453:epidemiology
chemical_list: D000068717:Glatiramer Acetate; D016899:Interferon-beta
keywords: adherence; hospitalizations; multiple sclerosis; pharmacoepidemiology