Objective: To validate the use of the English version of the PAS in Parkinson’s disease (PD) patients in Canada.

Background: The PAS, originally developed to assess the severity of anxiety symptoms in PD patients, is a 12-item observer- or patient-rated scale with three subscales that evaluate persistent anxiety, episodic anxiety, and avoidance behaviour. The initial validation study has examined its reliability and validity in a sample of PD patients from the United States, Europe, and Australia [1], but little evidence has been provided for its use in Canadian patients.

Method: Data from two study cohorts were included in this interim report. Cohort 1 consisted of 81 PD patients screened for the Treating Anxiety in Parkinson’s Disease With a Multi-Strain Probiotic study (NCT03968133). Cohort 2 consisted of 113 PD patients enrolled in a longitudinal observational study at the Pacific Parkinson’s Research Centre in Canada. Both cohorts were evaluated using the patient-rated PAS and the Beck Depression Inventory (BDI). Cohort 2 was additionally assessed using the MDS-Unified Parkinson’s Disease Rating Scale (MDS-UPDRS) and Starkstein Apathy Scale (SAS). Psychometric properties of the PAS, including internal consistency reliability, convergent and divergent validity, and factor structure were examined.

Results: Cronbach’s α for total scale scores was 0.87 for both cohorts, indicating good internal consistency. Cronbach’s α for the persistent, episodic and avoidance behaviour subscales was acceptable (Cohort 1: 0.83, 0.72, 0.73; Cohort 2: 0.88, 0.68, 0.72). The PAS demonstrated good convergent and divergent validity in Cohort 2, with moderately strong correlations with the BDI (r = 0.59, p < .001) and MDS-UPDRS 1.4 item (anxiety) (r = 0.56, p < .001), and a weak correlation with the SAS (r = 0.33, p < .001). The factor structure was examined with the larger Cohort 2 via confirmatory factor analysis (CFA). A three-factor model showed an adequate fit (comparative fit index = 0.97, Tucker-Lewis index = 0.96, root mean square error of approximation = 0.06, standardized root mean square residual = 0.06) [2], supporting the a priori three-factor structure of the PAS derived from the original study.

Conclusion: Our interim results provide strong psychometric evidence for the use of the PAS as a reliable and valid tool for measuring anxiety in Canadian PD patients.

References: [1] Leentjens, A.F.G., Dujardin, K., Pontone, G.M., Starkstein, S.E., Weintraub, D., Martinez-Martin, P. (2014). The Parkinson Anxiety Scale (PAS): Development and validation of a new anxiety scale. Movement Disorders, 29(8): 1035-1043. [2] Hu, L., Bentler, P.M. (1999). Cutoff criteria for fit indexes in covariance structure analysis: Conventional criteria versus new alternatives. Structural Equation Modeling: A Multidisciplinary Journal, 6(1): 1-55.

« Back to 2022 International Congress

MDS Abstracts - https://www.mdsabstracts.org/abstract/validation-of-the-english-version-of-the-parkinson-anxiety-scale-in-the-canadian-population-interim-results/