title: Analyzing differences between patient and proxy on Patient Reported Outcomes in multiple sclerosis.
abstract: BACKGROUND
  Proxy respondents, partners of multiple sclerosis (MS) patients, can provide valuable information on the MS patients' disease. In an earlier publication we found relatively good agreement on patient reported outcomes (PROs) measuring physical impact and functioning, but we found large differences on (neuro)psychological scales.
  
  
  OBJECTIVE
  We aim to identify patient and proxy related variables explaining differences between patients' and proxies' ratings on five PROs.
  
  
  METHODS
  We report on data from 175 MS patients and proxy respondents. Regression analyses were performed, using as dependent variable the mean differences on five scales: Physical and Psychological scale of the Multiple Sclerosis Impact Scale (MSIS-29), the Multiple Sclerosis Walking Scale (MSWS), Guy's Neurological Disability Scale (GNDS) and the Multiple Sclerosis Neuropsychological Screening Questionnaire (MSNQ). The independent variables were patient, proxy and disease related variables.
  
  
  RESULTS
  Caregiver strain was significantly related to differences between patient and proxy scores for all five PROs. A higher level of patient anxiety on the HADS was linked to larger differences on all PROs except the GNDS. In addition, cognitive functioning, proxy depression, walking ability, proxy gender and MS related disability were contributing to the discrepancies.
  
  
  CONCLUSIONS
  We found several patient and proxy factors that may contribute to discrepancies between patient and proxy scores on MS PROs. The most important factor is caregiver burden.
authors.affiliation: Department of Epidemiology and Biostatistics, VU University Medical Center, Amsterdam, The Netherlands; Department of Neurology, VU University Medical Center, Amsterdam, The Netherlands. Electronic address: Judith.sonder@vumc.nl.
authors.forename: Judith M
authors.initials: JM
authors.lastname: Sonder
authors.forename: Rebecca
authors.initials: R
authors.lastname: Holman
authors.forename: Dirk L
authors.initials: DL
authors.lastname: Knol
authors.forename: Libertje V A E
authors.initials: LV
authors.lastname: Bosma
authors.forename: Chris H
authors.initials: CH
authors.lastname: Polman
authors.forename: Bernard M J
authors.initials: BM
authors.lastname: Uitdehaag
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006304:Health Status; D006801:Humans; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000503:physiopathology / Q000523:psychology*; D009483:Neuropsychological Tests; D019727:Proxy / Q000523:psychology*; D011569:Psychiatric Status Rating Scales; D012044:Regression Analysis; D057566:Self Report; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires
keywords: Agreement; Multiple sclerosis; Outcome measurement; PRO; Patient reported outcome; Proxy measurement