title: Applying Rasch analysis to evaluate measurement equivalence of different administration formats of the Activity Limitation scale of the Cambridge Pulmonary Hypertension Outcome Review (CAMPHOR).
abstract: BACKGROUND
  Electronic formats of patient-reported outcome (PRO) measures are now routinely used in clinical research studies. When changing from a validated paper and pen to electronic administration it is necessary to establish their equivalence. This study reports on the value of Rasch analysis in this process.
  
  
  METHODS
  Three groups of US pulmonary hypertension (PH) patients participated. The first completed an electronic version of the CAMPHOR Activity Limitation scale (e-sample) and this was compared with two pen and paper administrated samples (pp1 and pp2). The three databases were combined and analysed for fit to the Rasch model. Equivalence was evaluated by differential item functioning (DIF) analyses.
  
  
  RESULTS
  The three datasets were matched randomly in terms of sample size (n = 147). Mean age (years) and percentage of male respondents were as follows: e-sample (51.7, 16.0 %); pp1 (50.0, 14.0 %); pp2 (55.5, 40.4 %). The combined dataset achieved fit to the Rasch model. Two items showed evidence of borderline DIF. Further analyses showed the inclusion of these items had little impact on Rasch estimates indicating the DIF identified was unimportant.
  
  
  CONCLUSIONS
  Differences between the performance of the electronic and pen and paper administrations of the CAMPHOR Activity Limitation scale were minor. The results were successful in showing how the Rasch model can be used to determine the equivalence of alternative formats of PRO measures.
authors.affiliation: Galen Research, B1 Chorlton Mill, 3 Cambridge Street, Manchester, M1 5BY, UK. jtwiss@galen-research.com.
authors.forename: J
authors.initials: J
authors.lastname: Twiss
authors.affiliation: Galen Research, B1 Chorlton Mill, 3 Cambridge Street, Manchester, M1 5BY, UK.
authors.forename: S P
authors.initials: SP
authors.lastname: McKenna
authors.affiliation: Galen Research, B1 Chorlton Mill, 3 Cambridge Street, Manchester, M1 5BY, UK.
authors.forename: J
authors.initials: J
authors.lastname: Graham
authors.affiliation: Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: K
authors.initials: K
authors.lastname: Swetz
authors.affiliation: Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: J
authors.initials: J
authors.lastname: Sloan
authors.affiliation: University of Chicago Medical Center, Chicago, Illinois, USA.
authors.forename: M
authors.initials: M
authors.lastname: Gomberg-Maitland
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D019985:Benchmarking; D057286:Electronic Health Records; D005260:Female; D006801:Humans; D006976:Hypertension, Pulmonary / Q000523:psychology*; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D017063:Outcome Assessment, Health Care / Q000379:methods* / Q000706:statistics & numerical data*; D010209:Paper; D010361:Patients / Q000523:psychology*; D011788:Quality of Life / Q000523:psychology*; D011795:Surveys and Questionnaires; D055815:Young Adult
keywords: Cambridge Pulmonary Hypertension Outcome Review (CAMPHOR); Electronic validation; Item response theory (IRT); Measurement equivalence; Patient reported outcome (PRO) measures; Rasch analysis