title: Psychometric evaluation of the Rasch-based depression screening in patients with neurologic disorders.
abstract: OBJECTIVE
  To provide a first evaluation of the Rasch-Based Depression Screening (DESC) in consecutive patients with neurologic disorders.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  Hospital specializing in neurologic disorders.
  
  
  METHODS
  Eligible patients (N=323; mean age +/- SD, 53.4+/-17.2y; 49.3% women) age 18 years and older.
  
  
  METHODS
  Not applicable.
  
  
  METHODS
  DESC with 2 parallel versions.
  
  
  RESULTS
  Both versions of the DESC showed good item separation (DESC-I=4.96; DESC-II=4.94) and person separation (DESC-I=2.01; DESC-II=2.14) as well as item separation reliability (DESC-I=.96; DESC-II=.96) and person separation reliability (DESC-I=.80; DESC-II=.82). All items fit the Rasch model (infit and outfit mean squares < or =1.3). There were no signs of violation of unidimensionality. One item of DESC-I showed differential item functioning because of age and 1 item because of sex. Parallel test reliability of the 2 DESC forms was r equal to .92.
  
  
  CONCLUSIONS
  The DESC shows good psychometric characteristics that suggest high psychometric quality of the instrument in patients with neurologic disorders. Differential item functioning on single items needs further examination but should not substantially interfere with the valid interpretation of DESC sum scores.
authors.affiliation: Institute of Medical Psychology and Medical Sociology, University Hospital of Rheinisch-Westfälische Technische Hochschule, Aachen, Germany. tforkmann@ukaachen.de
authors.forename: Thomas
authors.initials: T
authors.lastname: Forkmann
authors.forename: Christine
authors.initials: C
authors.lastname: Norra
authors.forename: Markus
authors.initials: M
authors.lastname: Wirtz
authors.forename: Siegfried
authors.initials: S
authors.lastname: Gauggel
authors.forename: Maren
authors.initials: M
authors.lastname: Boecker
mesh_terms: D000328:Adult; D000368:Aged; D003430:Cross-Sectional Studies; D003866:Depressive Disorder / Q000150:complications* / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009422:Nervous System Diseases / Q000150:complications*; D026741:Physical Therapy Modalities; D011594:Psychometrics; D012680:Sensitivity and Specificity