title: Use of Rasch analysis to refine a patient-reported questionnaire on satisfaction with communication of the multiple sclerosis diagnosis.
abstract: The Comunicazione medico-paziente nella Sclerosi Multipla - Revised (COSM-R) is a patient self-assessed questionnaire probing the moment of multiple sclerosis (MS) diagnosis disclosure (section 1, five items) and following period (section 2, 15 items).
  
  
  
  This study examined COSM-R dimensionality and measurement properties through Rasch analysis (partial-credit model) and proposed a revised questionnaire.
  
  
  
  Cross-sectional COSM-R data were obtained from 1068 people with MS (PwMS, 1065 questionnaires) participating in four studies (102 centres). Mean age was 40 years (range 17-73); 70% were women; 53% were from Northern, 25% from Central, and 21% from Southern Italy.
  
  
  
  Unidimensionality was not confirmed for COSM-R section 1, but was for section 2 after removal of three items. The revised instrument (COSM-S, Shortened) consisted of the original five-item checklist (section 1), modified by removing the table grouping of three items, and 12 of the original 15 section 2 items, which could now be summed and transformed into an interval scale. Scores were higher for items assessing emotional satisfaction than for those assessing informational satisfaction.
  
  
  
  The proposed COSM-S is a composite measure of satisfaction with MS diagnosis communication with improved metric properties over the original COSM-R, and whose section 2 satisfies Rasch model expectations.
authors.affiliation: Unit of Neuroepidemiology, Foundation IRCCS Neurological Institute C. Besta, Italy solari@istituto-besta.it.
authors.forename: A
authors.initials: A
authors.lastname: Solari
authors.affiliation: Department of Sociology, Faculty of Social Sciences, Warsaw University of Life Sciences, Poland Department of Neurorehabilitation Sciences, IRCCS Istituto Auxologico Italiano, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Grzeda
authors.affiliation: Unit of Neuroepidemiology, Foundation IRCCS Neurological Institute C. Besta, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Giordano
authors.affiliation: Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, Italy.
authors.forename: K
authors.initials: K
authors.lastname: Mattarozzi
authors.affiliation: Neuroepidemiology Unit, IRCCS Istituto delle Scienze Neurologiche di Bologna, Italy.
authors.forename: R
authors.initials: R
authors.lastname: D'Alessandro
authors.affiliation: Department of Neurorehabilitation Sciences, IRCCS Istituto Auxologico Italiano, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Simone
authors.affiliation: Department of Neurorehabilitation Sciences, IRCCS Istituto Auxologico Italiano, Italy Department of Biomedical Sciences for Health, University of Milan, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Tesio
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001291:Attitude of Health Personnel; D057189:Checklist; D003142:Communication; D003430:Cross-Sectional Studies; D004644:Emotions; D005260:Female; D006801:Humans; D007558:Italy; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000175:diagnosis* / Q000523:psychology; D017060:Patient Satisfaction; D010817:Physician-Patient Relations; D011594:Psychometrics; D057566:Self Report; D055815:Young Adult
keywords: Multiple sclerosis; Rasch analysis; diagnosis communication; patient satisfaction; validation studies