Background: The Shared Decision Making (SDM) model allows the patient to be part of their own disease treatment and control. The translation to Spanish of a questionnaire that measures the patient perception of SDM will allow enlarging the range of its application. However, the essence of the questionnaire can be altered during its translation, which could curb the appreciation of the question and what the question originally asked for. The objective of this study is to evaluate the application of SDM-Q-9 in its psychometric properties, to a Spanish speaking population after its translation process.
Method: The questionnaire was given to 76 outpatients who attended a medical control at the hospital. The informed consent process was developed before the patient underwent the physician's evaluation, and the SDM-Q-9 was applied when the patient finished the medical evaluation. The reliability of the questionnaire was evaluated and its structural validity was verified by the exploratory factor analysis (EFA) and the confirmatory factor analysis (CFA).
Results: The SDM-Q-9 presented reliability and validity according to the following indicators. The internal consistency, measured by Cronbach's alpha, was 0.839 for the whole scale. The EFA showed a bi-dimensional solution, but the CFA indicated that the model with best indices of fit was the one-dimensional solution, excluding the first item. The indices used where: CFI 0.953, RMSEA (IC) 0.076 (0.000-0.134) for model 2, and CFI 0.961, RMSEA 0.071 (0.000-0.132) for model 5 are better.
Conclusion: The questionnaire adaptation to the Latin American Spanish language has displayed reliability and validity according to the Cronbach's alpha indicators.
Keywords: Confirmatory factor analysis; Diabetes mellitus; Doctor-patient relationship; Psychometrics; SDM-Q-9 questionnaire; Shared decision making.