title: Examining the effects of comorbidities on disease-modifying therapy use in multiple sclerosis.
abstract: OBJECTIVE
  Comorbidities are common in multiple sclerosis (MS) and adversely affect health outcomes. However, the effect of comorbidity on treatment decisions in MS remains unknown. We aimed to examine the effects of comorbidity on initiation of injectable disease-modifying therapies (DMTs) and on the choice of the initial DMT in MS.
  
  
  METHODS
  We conducted a retrospective observational analysis using population-based health administrative and linked clinical databases in 3 Canadian provinces. MS cases were defined as any individual with ≥3 diagnostic codes for MS. Cohort entry (index date) was the first recorded demyelinating disease-related claim. The outcomes included choice of initial first-line DMTs and time to initiating a DMT. Logistic and Cox regression models were used to examine the association between comorbidity status and study outcomes, adjusting for sex, age, year of index date, and socioeconomic status. Meta-analysis was used to estimate overall effects across the 3 provinces.
  
  
  RESULTS
  We identified 10,698 persons with incident MS, half of whom had ≥1 comorbidities. As the total number of comorbidities increased, the likelihood of initiating a DMT decreased. Comorbid anxiety and ischemic heart disease were associated with reduced initiation of a DMT. However, patients with depression were 13% more likely to initiate a DMT compared to those without depression at the index date (adjusted hazard ratio 1.13; 95% confidence interval 1.00-1.27).
  
  
  CONCLUSIONS
  Comorbidities are associated with treatment decisions regarding DMTs in MS. A better understanding of the effects of comorbidity on effectiveness and safety of DMTs is needed.
authors.affiliation: From the Department of Medicine, Division of Neurology and Centre for Brain Health (T.Z., H.T., F.Z., E.K.), University of British Columbia, Vancouver; Department of Community Health Sciences (S.L., B.N.Y., R.A.M.), University of Manitoba, Winnipeg; Departments of Medicine (J.D.F., V.B., T.L.C.) and Psychiatry (J.D.F.) and School of Nursing (T.L.C.), Dalhousie University, Halifax, Nova Scotia; and Queen Elizabeth II Health Sciences Centre (J.D.F., V.B., T.L.C., K.S.), Nova Scotia Health Authority, Halifax, Canada.
authors.forename: Tingting
authors.initials: T
authors.lastname: Zhang
authors.affiliation: From the Department of Medicine, Division of Neurology and Centre for Brain Health (T.Z., H.T., F.Z., E.K.), University of British Columbia, Vancouver; Department of Community Health Sciences (S.L., B.N.Y., R.A.M.), University of Manitoba, Winnipeg; Departments of Medicine (J.D.F., V.B., T.L.C.) and Psychiatry (J.D.F.) and School of Nursing (T.L.C.), Dalhousie University, Halifax, Nova Scotia; and Queen Elizabeth II Health Sciences Centre (J.D.F., V.B., T.L.C., K.S.), Nova Scotia Health Authority, Halifax, Canada.
authors.forename: Helen
authors.initials: H
authors.lastname: Tremlett
authors.affiliation: From the Department of Medicine, Division of Neurology and Centre for Brain Health (T.Z., H.T., F.Z., E.K.), University of British Columbia, Vancouver; Department of Community Health Sciences (S.L., B.N.Y., R.A.M.), University of Manitoba, Winnipeg; Departments of Medicine (J.D.F., V.B., T.L.C.) and Psychiatry (J.D.F.) and School of Nursing (T.L.C.), Dalhousie University, Halifax, Nova Scotia; and Queen Elizabeth II Health Sciences Centre (J.D.F., V.B., T.L.C., K.S.), Nova Scotia Health Authority, Halifax, Canada.
authors.forename: Stella
authors.initials: S
authors.lastname: Leung
authors.affiliation: From the Department of Medicine, Division of Neurology and Centre for Brain Health (T.Z., H.T., F.Z., E.K.), University of British Columbia, Vancouver; Department of Community Health Sciences (S.L., B.N.Y., R.A.M.), University of Manitoba, Winnipeg; Departments of Medicine (J.D.F., V.B., T.L.C.) and Psychiatry (J.D.F.) and School of Nursing (T.L.C.), Dalhousie University, Halifax, Nova Scotia; and Queen Elizabeth II Health Sciences Centre (J.D.F., V.B., T.L.C., K.S.), Nova Scotia Health Authority, Halifax, Canada.
authors.forename: Feng
authors.initials: F
authors.lastname: Zhu
authors.affiliation: From the Department of Medicine, Division of Neurology and Centre for Brain Health (T.Z., H.T., F.Z., E.K.), University of British Columbia, Vancouver; Department of Community Health Sciences (S.L., B.N.Y., R.A.M.), University of Manitoba, Winnipeg; Departments of Medicine (J.D.F., V.B., T.L.C.) and Psychiatry (J.D.F.) and School of Nursing (T.L.C.), Dalhousie University, Halifax, Nova Scotia; and Queen Elizabeth II Health Sciences Centre (J.D.F., V.B., T.L.C., K.S.), Nova Scotia Health Authority, Halifax, Canada.
authors.forename: Elaine
authors.initials: E
authors.lastname: Kingwell
authors.affiliation: From the Department of Medicine, Division of Neurology and Centre for Brain Health (T.Z., H.T., F.Z., E.K.), University of British Columbia, Vancouver; Department of Community Health Sciences (S.L., B.N.Y., R.A.M.), University of Manitoba, Winnipeg; Departments of Medicine (J.D.F., V.B., T.L.C.) and Psychiatry (J.D.F.) and School of Nursing (T.L.C.), Dalhousie University, Halifax, Nova Scotia; and Queen Elizabeth II Health Sciences Centre (J.D.F., V.B., T.L.C., K.S.), Nova Scotia Health Authority, Halifax, Canada.
authors.forename: John D
authors.initials: JD
authors.lastname: Fisk
authors.affiliation: From the Department of Medicine, Division of Neurology and Centre for Brain Health (T.Z., H.T., F.Z., E.K.), University of British Columbia, Vancouver; Department of Community Health Sciences (S.L., B.N.Y., R.A.M.), University of Manitoba, Winnipeg; Departments of Medicine (J.D.F., V.B., T.L.C.) and Psychiatry (J.D.F.) and School of Nursing (T.L.C.), Dalhousie University, Halifax, Nova Scotia; and Queen Elizabeth II Health Sciences Centre (J.D.F., V.B., T.L.C., K.S.), Nova Scotia Health Authority, Halifax, Canada.
authors.forename: Virender
authors.initials: V
authors.lastname: Bhan
authors.affiliation: From the Department of Medicine, Division of Neurology and Centre for Brain Health (T.Z., H.T., F.Z., E.K.), University of British Columbia, Vancouver; Department of Community Health Sciences (S.L., B.N.Y., R.A.M.), University of Manitoba, Winnipeg; Departments of Medicine (J.D.F., V.B., T.L.C.) and Psychiatry (J.D.F.) and School of Nursing (T.L.C.), Dalhousie University, Halifax, Nova Scotia; and Queen Elizabeth II Health Sciences Centre (J.D.F., V.B., T.L.C., K.S.), Nova Scotia Health Authority, Halifax, Canada.
authors.forename: Trudy L
authors.initials: TL
authors.lastname: Campbell
authors.affiliation: From the Department of Medicine, Division of Neurology and Centre for Brain Health (T.Z., H.T., F.Z., E.K.), University of British Columbia, Vancouver; Department of Community Health Sciences (S.L., B.N.Y., R.A.M.), University of Manitoba, Winnipeg; Departments of Medicine (J.D.F., V.B., T.L.C.) and Psychiatry (J.D.F.) and School of Nursing (T.L.C.), Dalhousie University, Halifax, Nova Scotia; and Queen Elizabeth II Health Sciences Centre (J.D.F., V.B., T.L.C., K.S.), Nova Scotia Health Authority, Halifax, Canada.
authors.forename: Karen
authors.initials: K
authors.lastname: Stadnyk
authors.affiliation: From the Department of Medicine, Division of Neurology and Centre for Brain Health (T.Z., H.T., F.Z., E.K.), University of British Columbia, Vancouver; Department of Community Health Sciences (S.L., B.N.Y., R.A.M.), University of Manitoba, Winnipeg; Departments of Medicine (J.D.F., V.B., T.L.C.) and Psychiatry (J.D.F.) and School of Nursing (T.L.C.), Dalhousie University, Halifax, Nova Scotia; and Queen Elizabeth II Health Sciences Centre (J.D.F., V.B., T.L.C., K.S.), Nova Scotia Health Authority, Halifax, Canada.
authors.forename: B Nancy
authors.initials: BN
authors.lastname: Yu
authors.affiliation: From the Department of Medicine, Division of Neurology and Centre for Brain Health (T.Z., H.T., F.Z., E.K.), University of British Columbia, Vancouver; Department of Community Health Sciences (S.L., B.N.Y., R.A.M.), University of Manitoba, Winnipeg; Departments of Medicine (J.D.F., V.B., T.L.C.) and Psychiatry (J.D.F.) and School of Nursing (T.L.C.), Dalhousie University, Halifax, Nova Scotia; and Queen Elizabeth II Health Sciences Centre (J.D.F., V.B., T.L.C., K.S.), Nova Scotia Health Authority, Halifax, Canada. rmarrie@hsc.mb.ca.
authors.forename: Ruth Ann
authors.initials: RA
authors.lastname: Marrie
mesh_terms: D000293:Adolescent; D000328:Adult; D001955:British Columbia / Q000453:epidemiology; D015897:Comorbidity; D005260:Female; D000068717:Glatiramer Acetate / Q000627:therapeutic use*; D006801:Humans; D007155:Immunologic Factors / Q000627:therapeutic use*; D016899:Interferon-beta / Q000627:therapeutic use*; D008297:Male; D008350:Manitoba / Q000453:epidemiology; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000188:drug therapy* / Q000453:epidemiology*; D009674:Nova Scotia / Q000453:epidemiology; D012189:Retrospective Studies; D055815:Young Adult
chemical_list: D007155:Immunologic Factors; D000068717:Glatiramer Acetate; D016899:Interferon-beta