title: Improving the psychometric utility of the hypomania checklist (HCL-32): a Rasch analysis approach.
abstract: BACKGROUND
  The HCL-32 is a widely-used screening questionnaire for hypomania. We aimed to use a Rasch analysis approach to (i) evaluate the measurement properties, principally unidimensionality, of the HCL-32, and (ii) generate a score table to allow researchers to convert raw HCL-32 scores into an interval-level measurement which will be more appropriate for statistical analyses.
  
  
  METHODS
  Subjects were part of the Bipolar Disorder Research Network (BDRN) study with DSM-IV bipolar disorder (n=389). Multidimensionality was assessed using the Rasch fit statistics and principle components analysis of the residuals (PCA). Item invariance (differential item functioning, DIF) was tested for gender, bipolar diagnosis and current mental state. Item estimates and reliabilities were calculated.
  
  
  RESULTS
  Three items (29, 30, 32) had unacceptable fit to the Rasch unidimensional model. Item 14 displayed significant DIF for gender and items 8 and 17 for current mental state. Item estimates confirmed that not all items measure hypomania equally.
  
  
  CONCLUSIONS
  This sample was recruited as part of a large ongoing genetic epidemiology study of bipolar disorder and may not be fully representative of the broader clinical population of individuals with bipolar disorder.
  
  
  CONCLUSIONS
  The HCL-32 is unidimensional in practice, but measurements may be further strengthened by the removal of four items. Re-scored linear measurements may be more appropriate for clinical research.
authors.affiliation: Institute of Health and Wellbeing, University of Glasgow, UK. Electronic address: helen.court@glasgow.ac.uk.
authors.forename: Helen
authors.initials: H
authors.lastname: Court
authors.forename: Liz
authors.initials: L
authors.lastname: Forty
authors.forename: Lisa
authors.initials: L
authors.lastname: Jones
authors.forename: Katherine
authors.initials: K
authors.lastname: Gordon-Smith
authors.forename: Ian
authors.initials: I
authors.lastname: Jones
authors.forename: Nick
authors.initials: N
authors.lastname: Craddock
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Smith
mesh_terms: D000328:Adult; D001714:Bipolar Disorder / Q000175:diagnosis* / Q000523:psychology; D057189:Checklist / Q000592:standards*; D005260:Female; D006801:Humans; D008297:Male; D011594:Psychometrics; D012737:Sex Factors; D011795:Surveys and Questionnaires / Q000592:standards
keywords: Bipolar disorder; HCL-32; Hypomania; Multidimensionality; Rasch analysis; Screening