title: Measurement properties of painDETECT: Rasch analysis of responses from community-dwelling adults with neuropathic pain.
abstract: BACKGROUND
  painDETECT (PD-Q) is a self-reported assessment of pain qualities developed as a screening tool for pain of neuropathic origin. Rasch analysis is a strategy for examining the measurement characteristics of a scale using a form of item response theory. We conducted a Rasch analysis to consider if the scoring and measurement properties of PD-Q would support its use as an outcome measure.
  
  
  METHODS
  Rasch analysis was conducted on PD-Q scores drawn from a cross-sectional study of the burden and costs of NeP. The analysis followed an iterative process based on recommendations in the literature, including examination of sequential scoring categories, unidimensionality, reliability and differential item function. Data from 624 persons with a diagnosis of painful diabetic polyneuropathy, small fibre neuropathy, and neuropathic pain associated with chronic low back pain, spinal cord injury, HIV-related pain, or chronic post-surgical pain was used for this analysis.
  
  
  RESULTS
  PD-Q demonstrated fit to the Rasch model after adjustments of scoring categories for four items, and omission of the time course and radiating questions. The resulting seven-item scale of pain qualities demonstrated good reliability with a person-separation index of 0.79. No scoring bias (differential item functioning) was found for this version.
  
  
  CONCLUSIONS
  Rasch modelling suggests the seven pain-qualities items from PD-Q may be used as an outcome measure. Further research is required to confirm validity and responsiveness in a clinical setting.
authors.affiliation: School of Rehabilitation Sciences, McMaster University, 1400 Main St. W., Hamilton, ON, L8S 1C7, Canada. packhamt@hhsc.ca.
authors.forename: Tara L
authors.initials: TL
authors.lastname: Packham
authors.affiliation: Pfizer Inc, Groton, CT, USA.
authors.forename: Joseph C
authors.initials: JC
authors.lastname: Cappelleri
authors.affiliation: Pfizer Inc., New York, NY, USA.
authors.forename: Alesia
authors.initials: A
authors.lastname: Sadosky
authors.affiliation: School of Rehabilitation Sciences, McMaster University, 1400 Main St. W., Hamilton, ON, L8S 1C7, Canada.|School of Physical Therapy, Western University, London, Ontario, Canada.
authors.forename: Joy C
authors.initials: JC
authors.lastname: MacDermid
authors.affiliation: Department of Physical Medicine and Rheumatology, Balgrist University Hospital, Forchstrasse 340, CH-8008, Zurich, Switzerland.
authors.forename: Florian
authors.initials: F
authors.lastname: Brunner
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D057187:Independent Living; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D009437:Neuralgia / Q000175:diagnosis*; D010147:Pain Measurement / Q000379:methods*; D011594:Psychometrics / Q000379:methods*; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires
keywords: Neuropathic pain; Outcome measurement; PainDETECT; Rasch analysis