title: Adherence and persistence to drug therapies for multiple sclerosis: A population-based study.
abstract: OBJECTIVE
  We aimed to estimate the prevalence and predictors of optimal adherence and persistence to the disease-modifying therapies (DMT) for multiple sclerosis (MS) in 3 Canadian provinces.
  
  
  METHODS
  We used population-based administrative databases in British Columbia (BC), Saskatchewan, and Manitoba. All individuals receiving DMT (interferon-B-1b, interferon-B-1a, and glatiramer acetate) between 1-January-1996 and 31-December-2011 (BC), 31-March-2014 (Saskatchewan), or 31-March-2012 (Manitoba) were included. One-year adherence was estimated using the proportion of days covered (PDC). Persistence was defined as time to DMT discontinuation. Regression models were used to assess predictors of adherence and persistence; results were pooled using random effects meta-analysis.
  
  
  RESULTS
  4830 individuals were included. When results were combined, an estimated 76.4% (95% CI: 69.1-82.4%) of subjects exhibited optimal adherence (PDC ≥80%). Median time to discontinuation of the initial DMT was 1.9 years (95% CI: 1.6-2.1) in Manitoba, 2.8 years (95% CI: 2.5-3.0) in BC, and 4.0 years (95% CI: 3.5-4.6) in Saskatchewan. Age, sex and socioeconomic status were not associated with adherence or persistence. Individuals who had ≥4 physician visits during the year prior to the first DMT dispensation were more likely to exhibit optimal adherence compared to those with fewer (0-3) physician visits.
  
  
  CONCLUSIONS
  We observed adherence that is higher than what has been reported for other chronic diseases, and other non-population-based MS cohorts. Closer examination as to why adherence appears to be relatively better in MS and how adherence influences disease outcomes could contribute to our understanding of MS, and prove useful in the management of other chronic diseases.
authors.affiliation: College of Pharmacy & Nutrition, University of Saskatchewan, 104 Clinic Place, Saskatoon, SK S7N 5E5, Canada. Electronic address: charity.evans@usask.ca.
authors.forename: Charity
authors.initials: C
authors.lastname: Evans
authors.affiliation: Departments of Internal Medicine and Community Health Sciences, University of Manitoba, Health Sciences Centre, GF 543-820 Sherbrook Street, Winnipeg, MB, Canada R3A 1R9. Electronic address: rmarrie@hsc.mb.ca.
authors.forename: Ruth Ann
authors.initials: RA
authors.lastname: Marrie
authors.affiliation: Department of Medicine (Neurology), University of British Columbia, UBC Hospital, 2211 Wesbrook Mall, Vancouver, BC, Canada V6T 2B5. Electronic address: f.zhu@stat.ubc.ca.
authors.forename: Feng
authors.initials: F
authors.lastname: Zhu
authors.affiliation: Department of Community Health Sciences, University of Manitoba, Health Sciences Centre, GF 543-820 Sherbrook Street, Winnipeg, MB, Canada R3A 1R9. Electronic address: stellaleung1@gmail.com.
authors.forename: Stella
authors.initials: S
authors.lastname: Leung
authors.affiliation: Saskatchewan Health Quality Council, 241-111 Research Drive, Saskatoon, SK, Canada S7N 3R2. Electronic address: xlu@hqc.sk.ca.
authors.forename: Xinya
authors.initials: X
authors.lastname: Lu
authors.affiliation: Department of Community Health Sciences, University of Manitoba, Health Sciences Centre, GF 543-820 Sherbrook Street, Winnipeg, MB, Canada R3A 1R9. Electronic address: desyiz@gmail.com.
authors.forename: Dessalegn Y
authors.initials: DY
authors.lastname: Melesse
authors.affiliation: Department of Medicine (Neurology), University of British Columbia, UBC Hospital, 2211 Wesbrook Mall, Vancouver, BC, Canada V6T 2B5. Electronic address: elainejk@mail.ubc.ca.
authors.forename: Elaine
authors.initials: E
authors.lastname: Kingwell
authors.affiliation: Department of Medicine (Neurology), University of British Columbia, UBC Hospital, 2211 Wesbrook Mall, Vancouver, BC, Canada V6T 2B5. Electronic address: yinshan@msmri.medicine.ubc.ca.
authors.forename: Yinshan
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Department of Medicine (Neurology), University of British Columbia, UBC Hospital, 2211 Wesbrook Mall, Vancouver, BC, Canada V6T 2B5. Electronic address: helen.tremlett@ubc.ca.
authors.forename: Helen
authors.initials: H
authors.lastname: Tremlett
mesh_terms: D000328:Adult; D001955:British Columbia / Q000453:epidemiology; D015331:Cohort Studies; D005260:Female; D000068717:Glatiramer Acetate / Q000627:therapeutic use; D006801:Humans; D007155:Immunologic Factors / Q000627:therapeutic use; D000068556:Interferon beta-1a / Q000627:therapeutic use; D000068576:Interferon beta-1b / Q000627:therapeutic use; D008297:Male; D008350:Manitoba / Q000453:epidemiology; D009103:Multiple Sclerosis / Q000188:drug therapy* / Q000453:epidemiology* / Q000523:psychology; D012525:Saskatchewan / Q000453:epidemiology; D016903:Drug Monitoring
chemical_list: D007155:Immunologic Factors; D000068576:Interferon beta-1b; D000068717:Glatiramer Acetate; D000068556:Interferon beta-1a
keywords: Disease-modifying therapies; Medication adherence; Medication persistence; Multiple sclerosis