Comparing the nine-item Shared Decision-Making Questionnaire to the OPTION Scale - an attempt to establish convergent validity

Health Expect. 2015 Feb;18(1):137-50. doi: 10.1111/hex.12022. Epub 2012 Nov 26.


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.

Design: Cross-sectional study.

Setting and participants: 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.

Discussion: 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.

Conclusion: This study shows that the measurement of SDM remains challenging.

Keywords: convergent validity; measurement; psychometrics; shared decision-making.

Publication types

  • Research Support, Non-U.S. Gov't
  • Validation Study

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Chronic Disease
  • Cross-Sectional Studies
  • Decision Making*
  • Female
  • Germany
  • Humans
  • Male
  • Middle Aged
  • Outpatients
  • Patient Participation* / psychology
  • Physician-Patient Relations*
  • Psychometrics
  • Reproducibility of Results
  • Surveys and Questionnaires / standards*
  • Young Adult