title: Designing a new scale to measure anxiety symptoms in Parkinson's disease: item selection based on canonical correlation analysis.
abstract: OBJECTIVE
  The lack of appropriate measures has hindered the research on anxiety syndromes in Parkinson's disease (PD). The objective of the present cross-sectional, international study was to identify shared elements and grouping of components from anxiety scales as a basis for designing a new scale for use in PD.
  
  
  METHODS
  For this purpose, 342 consecutive PD patients were assessed by means of the Mini International Neuropsychiatric Inventory (depression and anxiety sections), the Clinical Global Impression of severity of the anxiety symptoms, the Hamilton Anxiety Rating Scale (HARS), the Neuropsychiatric Inventory (section E), the Beck Anxiety Inventory (BAI) and the Anxiety subscale of the Hospital Anxiety and Depression Scale (HADS-A).
  
  
  RESULTS
  As the HADS-A showed a weak correlation with the HARS and BAI, it was not considered for more analyses. HARS and BAI exploratory factor analysis identified nine factors (62% of the variance), with only two of them combining items from both scales. Therefore, a canonical correlation model (a method to identify relations between components of two groups of variables) was built and it showed four factors grouping items from both scales: the first factor corresponded to 'generalized anxiety'; the second factor included muscular, sensory and autonomic 'non-specific somatic symptoms'; the third factor was dominated by 'respiratory symptoms'; and the fourth factor included 'cardiovascular symptoms'.
  
  
  CONCLUSIONS
  BAI is heavily focused on panic symptoms, whilst HARS is more focused towards generalized anxiety symptoms. The new scale should include additional components in order to assess both episodic and persistent anxiety as well as items for evaluation of avoidance behaviour.
authors.affiliation: Alzheimer Center Reina Sofia Foundation and Consortium for Biomedical Research in Neurodegenerative Diseases, Carlos III Institute of Health, Madrid, Spain. pmartinez@fundacioncien.es
authors.forename: P
authors.initials: P
authors.lastname: Martinez-Martin
authors.forename: J M
authors.initials: JM
authors.lastname: Rojo-Abuin
authors.forename: K
authors.initials: K
authors.lastname: Dujardin
authors.forename: G M
authors.initials: GM
authors.lastname: Pontone
authors.forename: D
authors.initials: D
authors.lastname: Weintraub
authors.forename: M J
authors.initials: MJ
authors.lastname: Forjaz
authors.forename: S
authors.initials: S
authors.lastname: Starkstein
authors.forename: A F G
authors.initials: AF
authors.lastname: Leentjens
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001007:Anxiety / Q000175:diagnosis* / Q000209:etiology / Q000523:psychology*; D003072:Cognition Disorders / Q000209:etiology / Q000523:psychology; D003430:Cross-Sectional Studies; D003627:Data Interpretation, Statistical; D016208:Databases, Factual; D018450:Disease Progression; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000150:complications / Q000523:psychology*; D011569:Psychiatric Status Rating Scales / Q000706:statistics & numerical data; D015203:Reproducibility of Results
keywords: Parkinson's disease; anxiety; assessment; canonical correlation; rating scales