Testing psychometric properties of Shared Decision Making Questionnaire - Physician Version (SDM-Q-Doc) in an Italian real-world psychiatric clinical sample

Objectives. The Shared Decision Making Questionnaire-Physician Version (SDM-Q-Doc) is the main tool assessing SDM relationship between patient and physician using the clinician viewpoint. It is reliable in all medical fields, and the validation of its Italian ver-sion was still missing. Our aim was to validate the Italian version of the SDM-Q-Doc in a clinical sample of patients suffering from severe mental illness. Methods. We ap-proached 369 patients affected by major psychiatric disorders (including schizophrenia spectrum disorders, affective disorders and eating disorders) in a real-world outpatient clinical setting. We run the Confirmatory Fac-tor Analysis (CFA) to test the SDM-Q-Doc structure. We calculated the correlations between the SDM-Q-Doc and the Observing Patient Involvement (OPTION) scale, used as comparing test, and McDonald w coefficient to mea-sure convergent validity and internal consistency respec-tively. Results. We reached a response rate of 93.2% (344 final participants). The CFA showed a very good fit compared of the Italian version of SDM-Q-Doc (x2/ df=3.2, CFI=.99, TLI=.99, RMSEA=.08, SRMR=.04). We found several correlations between the SDM-Q-Doc and OPTION scale supporting a robust SDM-Q-Doc construct validity, while internal consistency of the scale was Mc-Donald w coefficient .92. Further, inter-item correlations ranged from .390 to .703, with a mean of .556. Conclu-sions. This study confirms the suitability of the Italian version of SDM-Q-Doc, with good reliability and sound-ness even when compared to other languages validated versions and to OPTION scale. SDM-Q-Doc represents an easy-to-use physician-centered measure to assess patients' involvement in medical decision-making, well performing in the Italian-speaking population.