Objective: To evaluate the reliability and validity of the English version of the Parkinson Anxiety Scale (PAS) in patients with Parkinson’s disease (PD).

Background: The PAS is a 12-item observer- or patient-rated scale that assesses the severity of anxiety symptoms in PD patients [1]. It has three subscales that evaluate persistent anxiety, episodic anxiety, and avoidance behaviour. While the PAS has been translated into several languages and is being increasingly used in clinical care and research, studies examining the psychometric and diagnostic properties of the English version of the PAS are limited to the initial validation by the scale developers.

Method: This study included 129 PD patients screened for the Treating Anxiety in Parkinson’s Disease with a Multi-Strain Probiotic trial (NCT03968133) at a large movement disorders clinic in Canada. Patients were assessed using the patient-rated PAS, the Beck Depression Inventory-II (BDI-II), and the Mini International Neuropsychiatric Interview (MINI), version 6.0.0. Psychometric properties of the PAS, including factor structure, internal consistency reliability, divergent validity, and criterion validity were examined.

Results: Results of confirmatory factor analysis indicated a good fit of the three-factor model to the data (comparative fit index = 0.987, Tucker-Lewis index = 0.983, root mean square error of approximation = 0.083, standardized root mean square residual = 0.087). The total scale and three subscales of the PAS all demonstrated good internal consistency, with Cronbach’s α ranging from 0.73 to 0.88. For divergent validity, the PAS was moderately correlated with the BDI-II (rho = 0.65, p < 0.001). About one fifth of patients (21.7%) were diagnosed with a current anxiety disorder based on the MINI. Receiver operating characteristic (ROC) curve analysis suggested that the optimal cut-off for the total PAS was 12.5, with an area under the ROC curve of 0.81, sensitivity of 0.89, specificity of 0.58, and Youden index of 1.47. This means having a PAS score ≥ 13 suggests the presence of an anxiety disorder. These values are similar to those reported by the initial validation [1]. The optimal cut-off was 8.5 for the persistent anxiety subscale and 2.5 for the episodic anxiety and avoidance behaviour subscales.

Conclusion: The English version of the PAS is a reliable and valid anxiety measure for use in PD patients.

Preliminary results were presented at the 2022 MDS Congress.

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. Mov Disord. 29(8): 1035-1043.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/reliability-and-validity-of-the-english-version-of-the-parkinson-anxiety-scale/