Anxiety in early Parkinson's disease: Validation of the Italian observer-rated version of the Parkinson Anxiety Scale (OR-PAS)

Introduction Anxiety disorders are common in Parkinson's Disease (PD) and their identification is relevant even at early stages. The Parkinson Anxiety Scale (PAS) evaluates anxiety in PD; it was used only in the original validation study in PD patients mainly at 2-3 stages of Hoehn & Yahr system (H&Y). The study aimed to investigate psychometric properties of observer-rated version of the PAS (OR-PAS), prevalence rate of anxiety and its features, compared with diagnostic criteria in early PD patients. Methods A sample of 101 PD patients with H&Y:1-2 underwent the OR-PAS. To assess convergent and divergent validity, PD patients underwent Beck Anxiety Inventory, and scales assessing depression, apathy, anhedonia and cognition. To diagnose anxiety disorders, Mini International Neuropsychiatric Inventory was used as gold standard. A "receiver operating characteristics" curve was obtained; positive and negative predictive values were calculated for different cut-off points of the OR-PAS and its subscales. Results There was no missing data, no floor and ceiling effects; mean score was 12.2 ± 10.1; Cronbach's alpha was 0.899. The OR-PAS showed good convergent and divergent validity. Maximum discrimination was obtained with a cut-off score of 8.5. The anxiety occurred in 59 patients (58.4%). Conclusion The OR-PAS is a reliable and valid screening instrument for assessing anxiety in patients at early PD. Anxiety was found in 58.4% of PD patients, demonstrating that anxiety occurs even at early stages.