title: Mental comorbidity and multiple sclerosis: validating administrative data to support population-based surveillance.
abstract: BACKGROUND
  While mental comorbidity is considered common in multiple sclerosis (MS), its impact is poorly defined; methods are needed to support studies of mental comorbidity. We validated and applied administrative case definitions for any mental comorbidities in MS.
  
  
  METHODS
  Using administrative health data we identified persons with MS and a matched general population cohort. Administrative case definitions for any mental comorbidity, any mood disorder, depression, anxiety, bipolar disorder and schizophrenia were developed and validated against medical records using a a kappa statistic (k). Using these definitions we estimated the prevalence of these comorbidities in the study populations.
  
  
  RESULTS
  Compared to medical records, administrative definitions showed moderate agreement for any mental comorbidity, mood disorders and depression (all k ≥ 0.49), fair agreement for anxiety (k = 0.23) and bipolar disorder (k = 0.30), and near perfect agreement for schizophrenia (k = 1.0). The age-standardized prevalence of all mental comorbidities was higher in the MS than in the general populations: depression (31.7% vs. 20.5%), anxiety (35.6% vs. 29.6%), and bipolar disorder (5.83% vs. 3.45%), except for schizophrenia (0.93% vs. 0.93%).
  
  
  CONCLUSIONS
  Administrative data are a valid means of surveillance of mental comorbidity in MS. The prevalence of mental comorbidities, except schizophrenia, is increased in MS compared to the general population.
authors: Department of Internal Medicine, University of Manitoba, Winnipeg, Canada. rmarrie@hsc.mb.ca
authors: Ruth Ann
authors: RA
authors: Marrie
authors: John D
authors: JD
authors: Fisk
authors: Bo Nancy
authors: BN
authors: Yu
authors: Stella
authors: S
authors: Leung
authors: Lawrence
authors: L
authors: Elliott
authors: Patricia
authors: P
authors: Caetano
authors: Sharon
authors: S
authors: Warren
authors: Charity
authors: C
authors: Evans
authors: Christina
authors: C
authors: Wolfson
authors: Lawrence W
authors: LW
authors: Svenson
authors: Helen
authors: H
authors: Tremlett
authors: James F
authors: JF
authors: Blanchard
authors: Scott B
authors: SB
authors: Patten
mesh_terms: D000328:Adult; D002170:Canada / Q000453:epidemiology; D015331:Cohort Studies; D015897:Comorbidity; D005260:Female; D006801:Humans; D008297:Male; D008499:Medical Records / Q000706:statistics & numerical data*; D001523:Mental Disorders / Q000453:epidemiology*; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000453:epidemiology*; D011159:Population Surveillance; D015995:Prevalence; D015203:Reproducibility of Results; D055815:Young Adult
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