RESUMEN
Purpose: We aimed to validate the Spanish version of the Decisional Conflict Scale (DCS) and analyze its psychometric properties in people with migraine. Patients and Methods: The DCS validation comprised two phases. First, a translation and cross-cultural adaptation following the International Society for Pharmacoeconomics and Outcomes Research (ISPOR) Good Practices: 1-preparation, 2-independent forward translation, 3-reconciliation, 4-back-translation, 5-harmonization, 6-clinical review, and 7-content validation in a group of migraine patients. Second, the analysis of the psychometric properties. The reliability or internal consistency of the DCS scale and subscales was assessed using Cronbach's α value. The item-subscale correlation was also evaluated. A floor and ceiling effects for DCS score was considered when at least 15% of respondents obtained DCS >90 (ceiling) or <10 (floor). The construct validity was studied through the correlation between the DCS subscales and by the correlation between the DCS and other questionnaires (Decision Self-Efficacy Scale [DSES] and 9-item Shared Decision-Making [SDM-Q-9]). Spearman's coefficients were estimated for the correlations. Results: The cross-cultural adaptation was conducted on 17 patients who completed the questionnaire in a mean of 2.4 ±1.1 minutes. Generally, more than 75% of them considered that DCS items were adequate, easy to understand, and relevant. The psychometric properties were evaluated in a sample of n=128 patients. Accordingly, the internal consistency of DCS was high, with a Cronbach's α of 0.97 for the scale and between 0.87 to 0.96 for subscales. Also, a slight floor effect was observed, with 24.2% of patients having DCS scores <10. The correlation between subscales exceeded Spearman's coefficient of 0.7. Whereas the correlation between the DCS and the other questionnaires was generally moderate (Spearman's coefficient >0.4). Conclusion: The Spanish version (Spain) of the DCS has very acceptable psychometric properties (reliability and construct validity) and good potential for assessing decisional conflicts among migraine patients.