Is the Parkinson Anxiety Scale Comparable Across Raters?

Maria Joao Forjaz*, Alba Ayala, Pablo Martinez-Martin, Kathy Dujardin, Gregory M. Pontone, Sergio E. Starkstein, Daniel Weintraub, Albert F. G. Leentjens

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review


The Parkinson Anxiety Scale is a new scale developed to measure anxiety severity in Parkinson's disease specifically. It consists of three dimensions: persistent anxiety, episodic anxiety, and avoidance behavior. This study aimed to assess the measurement properties of the scale while controlling for the rater (self- vs. clinician-rated) effect. The Parkinson Anxiety Scale was administered to a cross-sectional multicenter international sample of 362 Parkinson's disease patients. Both patients and clinicians rated the patient's anxiety independently. A many-facet Rasch model design was applied to estimate and remove the rater effect. The following measurement properties were assessed: fit to the Rasch model, unidimensionality, reliability, differential item functioning, item local independency, interrater reliability (self or clinician), and scale targeting. In addition, test-retest stability, construct validity, precision, and diagnostic properties of the Parkinson Anxiety Scale were also analyzed. A good fit to the Rasch model was obtained for Parkinson Anxiety Scale dimensions A and B, after the removal of one item and rescoring of the response scale for certain items, whereas dimension C showed marginal fit. Self versus clinician rating differences were of small magnitude, with patients reporting higher anxiety levels than clinicians. The linear measure for Parkinson Anxiety Scale dimensions A and B showed good convergent construct with other anxiety measures and good diagnostic properties. Parkinson Anxiety Scale modified dimensions A and B provide valid and reliable measures of anxiety in Parkinson's disease that are comparable across raters. Further studies are needed with dimension C.
Original languageEnglish
Pages (from-to)545-551
JournalMovement Disorders
Issue number4
Publication statusPublished - Apr 2015


  • Parkinson's disease
  • anxiety
  • Rasch analysis
  • rater


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