Cross-cultural adaptation and validation of the Swallowing Disturbance Questionnaire and the Sialorrhea Clinical Scale in Portuguese patients with Parkinson's disease.

INTRODUCTION: To date, no valid outcome measure has been developed in European Portuguese (EP) to evaluate the Parkinsons' Disease (PD) patients' (PwP) reports regarding their swallowing disturbances. OBJECTIVES: The aim of this study was to translate and cross-culturally adapt the Swallowing Disturbance Questionnaire (SDQ) and the Sialorrhea Clinical Scale for PD (SCS-PD) into EP and to determine its clinimetric properties in PwP. MATERIALS AND METHODS: The original English SDQ and SCS-PD versions were cross-culturally adapted following recommendations established in international guidelines. The validation process involved 75 PwP and 65 healthy sex- and age-matched participants. RESULTS: The EP versions of the SDQ and SCS-PD are equivalent to the original versions (content, depth, and scoring). Statistical analyses for the SDQ tool revealed good feasibility (missing data <5%), acceptability (no floor or ceiling effects), excellent internal consistency (Cronbach s alpha = 0.95), good construct validity (78.5% revealed large to moderate loadings), moderate convergent validity (r = 0.60), good divergent validity (r = 0.40), good known-groups validity (p-value < .05) and a fair sensitivity and specificity (AUC = 0.700). Statistical analyses for the SCS-PD tool shows good feasibility, reasonable acceptability (floor effect), good internal consistency (Cronbach s alpha = 0.85), good construct validity (85.7% showed between large to moderate loadings), good convergent validity (r = 0.78), good divergent validity (r = 0.39), good known groups validity (p-value < .05) and a fair sensitivity and specificity (AUC = 0.704). CONCLUSIONS: The EP versions of the SDQ and SCS-PD maintained the characteristics of the original versions and therefore consistent tools to be used in PwP.