title: Comparison of the paper-based and electronic versions of the Dermatology Life Quality Index: evidence of equivalence.
abstract: BACKGROUND
  The use of patient-reported outcome measures in electronic format has been increasing. However, these formats are usually not validated or compared with the original paper-based formats, so there is no evidence that they are completed in the same way.
  
  
  OBJECTIVE
  To compare the conventional paper version with a web-based application (iPad®) version of the Dermatology Life Quality Index (DLQI) to assess equivalence of scores.
  
  
  METHODS
  The study employed a randomized crossover design using a within-subjects comparison of the two formats of the questionnaire. International Society for Pharmacoeconomics and Outcomes Research (ISPOR) guidelines were followed. Participants aged over 18 years with any confirmed skin condition were recruited from a teaching hospital dermatology outpatient clinic. Expected intraclass correlation coefficient (ICC) was 0·9 (α = 0·05).
  
  
  RESULTS
  A total of 104 patients were recruited, median age 53·5 years (interquartile range 37·3-67·8; 43% male). The ICC showed high concordance between the total DLQI scores from paper and iPad versions (ICC 0·98; 95% confidence interval 0·97-0·99). Patients took a median of 78 s to complete the electronic version and 73 s for paper (P = 0·008): 76% preferred the electronic version and perceived completion to take a shorter time.
  
  
  CONCLUSIONS
  There is high concordance and thus equivalence between the iPad and paper versions of the DLQI, with an ICC of 0·98, and a clear patient preference for the iPad version.
authors.affiliation: Department of Dermatology and Wound Healing, Division of Infection and Immunity, School of Medicine, Cardiff University, Cardiff, U.K.
authors.forename: F M
authors.identifier: http://orcid.org/0000-0002-4184-2023
authors.initials: FM
authors.lastname: Ali
authors.affiliation: Department of Dermatology and Wound Healing, Division of Infection and Immunity, School of Medicine, Cardiff University, Cardiff, U.K.|Faculty of Pharmaceutical Sciences and Melatonin Research Group, Khon Kaen University, Khon Kaen, Thailand.
authors.forename: N
authors.initials: N
authors.lastname: Johns
authors.affiliation: Department of Dermatology and Wound Healing, Division of Infection and Immunity, School of Medicine, Cardiff University, Cardiff, U.K.
authors.forename: A Y
authors.identifier: http://orcid.org/0000-0003-2143-1646
authors.initials: AY
authors.lastname: Finlay
authors.affiliation: School of Life and Medical Sciences, University of Hertfordshire, Hatfield, U.K.|Institute for Medicines Development, Cardiff, U.K.
authors.forename: M S
authors.identifier: http://orcid.org/0000-0002-4612-5699
authors.initials: MS
authors.lastname: Salek
authors.affiliation: Department of Dermatology and Wound Healing, Division of Infection and Immunity, School of Medicine, Cardiff University, Cardiff, U.K.
authors.forename: V
authors.identifier: http://orcid.org/0000-0001-6079-4517
authors.initials: V
authors.lastname: Piguet
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018592:Cross-Over Studies; D057286:Electronic Health Records; D005260:Female; D006801:Humans; D008297:Male; D008499:Medical Records; D008875:Middle Aged; D000071066:Patient Reported Outcome Measures; D011788:Quality of Life / Q000523:psychology*; D015203:Reproducibility of Results; D012871:Skin Diseases / Q000523:psychology* / Q000628:therapy; D011795:Surveys and Questionnaires; D055815:Young Adult