Measuring shared decision making in oncology: Development and first testing of the iSHAREpatient and iSHAREphysician questionnaires

Health Expectations, vol. 23, pp. 496–508

Abstract

BACKGROUND: Existing measures to assess shared decision making (SDM) have often been developed based on an ill-defined underlying construct, and many assess physician behaviours only or focus on a single patient-physician encounter. OBJECTIVE: To (a) develop a patient and a physician questionnaire to measure SDM in oncology and (b) determine their content validity and comprehensibility. METHODS: A systematic review of SDM models and an oncology-specific SDM model informed the domains of the SDM construct. We formulated items for each SDM domain. Cancer patients and physicians rated content validity in an online questionnaire. We assumed a formative measurement model and performed online field-testing in cancer patients to inform further item reduction. We tested item comprehension in cognitive interviews with cancer patients and physicians. RESULTS: We identified 17 domains and formulated 132 items. Twelve cancer patients rated content validity at item level, and 11 physicians rated content validity at domain level. We field-tested the items among 131 cancer patients and conducted cognitive interviews with eight patients and five physicians. These phases resulted in the 15-item iSHAREpatient and 15-item iSHAREphysician questionnaires, covering 13 domains. CONCLUSIONS: We thoroughly developed the iSHARE questionnaires. They both assess patient and physician behaviours and cover the entire SDM process rather than a single consultation.

Authors 6

1. Hanna Bomhof‐Roordink Aachen Medical Decision Making Department of Biomedical Data Sciences

   Leiden University Medical Center

   Affiliation as printed

   Medical Decision Making Department of Biomedical Data Sciences Leiden University Medical Center Leiden The Netherlands

   Medical Decision Making, Department of Biomedical Data Sciences, Leiden University Medical Center, Leiden, The Netherlands

2. Fania R. Gärtner Aachen Medical Decision Making Department of Biomedical Data Sciences

   Leiden University Medical Center

   Affiliation as printed

   Medical Decision Making Department of Biomedical Data Sciences Leiden University Medical Center Leiden The Netherlands

   Medical Decision Making, Department of Biomedical Data Sciences, Leiden University Medical Center, Leiden, The Netherlands

3. Nanny van Duijn‐Bakker Aachen Medical Decision Making Department of Biomedical Data Sciences

   Leiden University Medical Center

   Affiliation as printed

   Medical Decision Making Department of Biomedical Data Sciences Leiden University Medical Center Leiden The Netherlands

   Medical Decision Making, Department of Biomedical Data Sciences, Leiden University Medical Center, Leiden, The Netherlands

4. Trudy van der Weijden

   Maastricht University · Care and Public Health Research Institute

   Affiliation as printed

   Department of Family Medicine CAPHRI School for Care and Public Health Research Institute Maastricht University Maastricht The Netherlands

   Department of Family Medicine, CAPHRI School for Care and Public Health Research Institute, Maastricht University, Maastricht, The Netherlands

5. Anne Margarethe Stiggelbout Aachen Medical Decision Making Department of Biomedical Data Sciences

   Leiden University Medical Center

   Affiliation as printed

   Medical Decision Making Department of Biomedical Data Sciences Leiden University Medical Center Leiden The Netherlands

   Medical Decision Making, Department of Biomedical Data Sciences, Leiden University Medical Center, Leiden, The Netherlands

6. Arwen H. Pieterse corresponding Aachen Medical Decision Making Department of Biomedical Data Sciences

   Leiden University Medical Center

   Affiliation as printed

   Medical Decision Making Department of Biomedical Data Sciences Leiden University Medical Center Leiden The Netherlands

   Medical Decision Making, Department of Biomedical Data Sciences, Leiden University Medical Center, Leiden, The Netherlands