Validation Study of the Parkinson's Disease Stigma Questionnaire (PDStigmaQuest).

Background: Stigma is a relevant aspect of Parkinson's disease (PD). Specific stigma tools are needed to address the complex construct of stigma in PD comprehensively.

Objective: To test the dimensionality and psychometric properties of the newly developed Parkinson's Disease Stigma Questionnaire (PDStigmaQuest).

Methods: In this multi-center, cross-sectional study including PD patients and healthy controls, the dimensionality of the PDStigmaQuest was examined through exploratory factor analysis. Acceptability and psychometric properties were investigated. PDStigmaQuest scores of patients and healthy controls were compared.

Results: In total, 201 PD patients and 101 healthy controls were included in the final analysis. Results suggested high data quality of the PDStigmaQuest (0.0001% missing data for patients). The exploratory factor analysis produced four factors: felt stigma, hiding, enacted stigma: rejection, and enacted stigma: patronization, explaining 47.9% of variance. An optional work domain for employed patients was included. Moderate floor effects and skewness, but no ceiling effects were found. Cronbach's alpha of 0.85 indicated high internal consistency. Calculated item-total correlations met standard criteria. Test-retest reliability was high (rs = 0.83). PDStigmaQuest scores correlated significantly with other stigma measures (rs = 0.56-0.69) and were significantly higher in patients than in healthy controls and higher in patients with depressive symptoms than in those without.

Conclusions: The patient-reported 18-item PDStigmaQuest showed strong psychometric properties of validity and reliability. Our results suggest that the PDStigmaQuest can be used to assess and evaluate stigma comprehensively in PD, which will improve our understanding of the construct of PD stigma.