title: Validation of a self-report comorbidity questionnaire for multiple sclerosis.
abstract: OBJECTIVE
  Researchers increasingly recognize the high frequency of comorbidity in multiple sclerosis (MS) and the negative impact on quality of life and disability, but little work has evaluated methods of comorbidity measurement in MS. We aimed to validate a self-report questionnaire for assessing comorbidity in MS.
  
  
  METHODS
  Patients with MS were recruited from the MS Clinic in Winnipeg, Canada and the Mellen Center (Cleveland Clinic, Cleveland, Ohio, USA) from October 2008 to 2009. Using a questionnaire, participants reported the presence or absence of 36 comorbidities, sociodemographic characteristics, and disability status. Abstractors blinded to questionnaire results collected data regarding the comorbidities of interest and their treatments. Using the medical record as the gold standard, we determined the sensitivity, specificity, positive and negative predictive values of the questionnaire data. To measure agreement we calculated kappa (kappa) statistics.
  
  
  RESULTS
  We enrolled 404 participants. Agreement between self-report and medical records was high (kappa >0.82) for diabetes and hypertension; substantial (kappa = 0.62-0.80) for hyperlipidemia, thyroid disease, glaucoma, and lung disease; moderate (kappa = 0.43-0.56) for osteoporosis, irritable bowel syndrome, migraine, depression, heart disease, and anxiety disorders. Agreement was slight to fair for the remaining comorbidities.
  
  
  CONCLUSIONS
  Self-report is a valid way to capture comorbidities affecting MS patients.
authors.affiliation: Department of Internal Medicine, University of Manitoba, Winnipeg, Man., Canada.
authors.forename: Myles
authors.initials: M
authors.lastname: Horton
authors.forename: Richard A
authors.initials: RA
authors.lastname: Rudick
authors.forename: Claire
authors.initials: C
authors.lastname: Hara-Cleaver
authors.forename: Ruth Ann
authors.initials: RA
authors.lastname: Marrie
mesh_terms: D000328:Adult; D015897:Comorbidity; D003710:Demography; D005260:Female; D006801:Humans; D008297:Male; D008350:Manitoba / Q000453:epidemiology; D008499:Medical Records; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000150:complications / Q000453:epidemiology*; D009820:Ohio / Q000453:epidemiology; D015203:Reproducibility of Results; D018401:Sample Size; D011795:Surveys and Questionnaires