Cancer types
  • General
Title of study
Shared decision making (SDM) in oncology: Developing and validating cancer patient and oncologist measures for realization of SDM
Version Number
Approval Date 
1.9, 3 August 2018
Short Title
Study site
Principle Investigator
A. Pieterse (LUMC)
Investigator Maastro
Prof. Dr. L. Boersma
Department of Biomedical Data Sciences, LUMC
Trial registry

• The first aim is to further clarify the construct of SDM in oncology, by means of two systematic reviews of the literature and the elicitation of patient, disease-free patient, doctor, nurse practitioner, member of the general population and expert perceptions of SDM. Underlying this aim is the finding that SDM measures from different perspectives and with different operationalizations are weakly correlated. Further, instruments mostly focus on doctor behavior and do not include patient cognitions and emotions. Moreover, few studies on instrument development so far have incorporated in-depth involvement of patients. Finally, important aspects typical for oncology, such as risk communication and preference construction, tend to be neglected in existing measures and studies from primary care may have used operationalizations that do not fit cancer patients’ perceptions
• The second aim is to find ways to operationalize SDM-realization in order to develop feasible, reliable and valid cancer patient and doctor questionnaires. The questionnaires will be based on the construct and operationalization clarified under objective 1. The patient questionnaire is central to this project. For doctors a brief questionnaire to assess realization of the SDM-construct will be developed
• The third aim is to validate, i.e., test the psychometric properties of the questionnaires, notably reliability and validity. We will assess test-retest reliability. We will assess construct validity. Construct validity will be assessed by testing several hypotheses regarding the relatedness of the I-SHARE questionnaires and questionnaires measuring similar or different constructs, and by testing known-group differences. . Hypotheses concerning the construct validity are based on review of the literature and expected correlations between elements of the I-SHARE questionnaires compared to subscales from other questionnaires, based on the content of the items

Primary Endpoint 

The psychometric properties of the I-SHARE questionnaire to measure SDM in oncology; this will consist of a version for patients and a version for doctors

Secondary Endpoints