title: A comparison of the Work and Social Adjustment Scale (WSAS) across different patient populations using Rasch analysis and exploratory factor analysis.
abstract: The Work and Social Adjustment Scale (WSAS) is designed to measure patients' perceived functional impairment associated with a health problem. There is a paucity of studies that explore the stability of the item hierarchy in the WSAS across different disease populations. This study investigated the unidimensional structure of the WSAS across different disease populations.
  
  
  
  Secondary data analysis was conducted on pooled patient data (HIV, breast cancer, and inflammatory conditions) to create a new dataset (n=554). The data were analysed using Rasch analysis and exploratory factor analysis.
  
  
  
  Exploratory factor analysis and principle component analysis of the WSAS showed a good fit as a unidimensional scale, person and item separation indices were >2 suggesting that the WSAS is sensitive enough to distinguish between participants of varying levels of ability. Some differential item functioning was seen by diagnosis and by sex for items 1 and 5 of the WSAS.
  
  
  
  Overall, a one dimensional structure was identified for the WSAS. However, a small number of differential item functioning (DIF) was identified, suggesting that scores from the WSAS cannot be compared across groups.
authors.affiliation: Academic Department of Military Mental Health, King's College London, UK. Electronic address: gursimran.thandi@kcl.ac.uk.
authors.forename: Gursimran
authors.initials: G
authors.lastname: Thandi
authors.affiliation: King's Centre for Military Mental Health, King's College London, London, UK.
authors.forename: Nicola T
authors.initials: NT
authors.lastname: Fear
authors.affiliation: Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK.
authors.forename: Trudie
authors.initials: T
authors.lastname: Chalder
mesh_terms: D000328:Adult; D004194:Disease / Q000523:psychology*; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010465:Perception; D011594:Psychometrics; D012917:Social Adjustment; D011795:Surveys and Questionnaires; D014937:Work / Q000523:psychology*
keywords: Functional impairment; Rasch analysis; Work and Social Adjustment Scale