title: Comparing the nine-item Shared Decision-Making Questionnaire to the OPTION Scale - an attempt to establish convergent validity.
abstract: BACKGROUND
  While there has been a clear move towards shared decision-making (SDM) in the last few years, the measurement of SDM-related constructs remains challenging. There has been a call for further psychometric testing of known scales, especially regarding validity aspects.
  
  
  OBJECTIVE
  To test convergent validity of the nine-item Shared Decision-Making Questionnaire (SDM-Q-9) by comparing it to the OPTION Scale.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  Data were collected in outpatient care practices. Patients suffering from chronic diseases and facing a medical decision were included in the study.
  
  
  METHODS
  Consultations were evaluated using the OPTION Scale. Patients completed the SDM-Q-9 after the consultation. First, the internal consistency of both scales and the inter-rater reliability of the OPTION Scale were calculated. To analyse the convergent validity of the SDM-Q-9, correlation between the patient (SDM-Q-9) and expert ratings (OPTION Scale) was calculated.
  
  
  RESULTS
  A total of 21 physicians provided analysable data of consultations with 63 patients. Analyses revealed good internal consistency of the SDM-Q-9 and limited internal consistency of the OPTION Scale. Inter-rater reliability of the latter was less than optimal. Association between the total scores of both instruments was weak with a Spearman correlation of r = 0.19 and did not reach statistical significance.
  
  
  CONCLUSIONS
  By the use of the OPTION Scale convergent validity of the SDM-Q-9 could not be established. Several possible explanations for this result are discussed.
  
  
  CONCLUSIONS
  This study shows that the measurement of SDM remains challenging.
authors.affiliation: Department of Medical Psychology, University Medical Center Hamburg-Eppendorf, Hamburg.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Scholl
authors.forename: Levente
authors.initials: L
authors.lastname: Kriston
authors.forename: Jörg
authors.initials: J
authors.lastname: Dirmaier
authors.forename: Martin
authors.initials: M
authors.lastname: Härter
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002908:Chronic Disease; D003430:Cross-Sectional Studies; D003657:Decision Making; D005260:Female; D005858:Germany; D006801:Humans; D008297:Male; D008875:Middle Aged; D010045:Outpatients; D010358:Patient Participation / Q000523:psychology; D010817:Physician-Patient Relations; D011594:Psychometrics; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires / Q000592:standards*; D055815:Young Adult