Psychometric Validation and Reliability of the 9-Item Shared Decision-Making Questionnaire: A Systematic Review.

Background: This study aimed to provide comprehensive information on translated versions of the 9-item shared decision-making questionnaire, widely used to measure patient involvement in shared decision-making, by combining psychometric validation information.

Methods: We searched various databases such as PubMed, Scopus, Google Scholar, along with developer website to gather pertinent literature published until Feb, 2024. This psychometric validation carried out based on item characteristics, content validity, and factor analysis results of individual studies. Our evaluation was based on predetermined cut-off values for item difficulty, discrimination index, Cronbach's alpha, Kaiser Meyer Olkin factor (KMO), Bartlett's test of sphericity, and factor extraction and rotation, confirmatory factor analysis range. The European Social Research Council guidance on the conduct of narrative synthesis in systematic reviews was employed for synthesis of validation results.

Results: The final analysis included nine studies with 3090 participants from various countries, and most participants had adequate literacy, and age range was 30-60 yr. Most model versions had a good fit, and all studies reported satisfactory results, except for one study's discrimination index values. The tool's validity was satisfactory. Most of the studies reported a convenient sample was the main limitation, along with recall bias in the final responses.

Conclusion: The 9-item shared decision-making tool can be used to measure patient involvement in shared decision-making in validated language-respected countries, as proper evaluation procedures reported satisfactory results in the confirmatory analysis models and reliability testing.