title: Lending a hand: can DASH items help ABILHAND improve manual ability measurement in multiple sclerosis?
abstract: BACKGROUND
  Our examination in multiple sclerosis (MS) of the ABILHAND, a patient-reported outcome (PRO) instrument measuring manual ability, identified limited measurement range and precision. These deficiencies could lead to type II errors in clinical trials.
  
  
  OBJECTIVE
  This paper aims to determine if ABILHAND's measurement performance in MS can be improved by adding relevant items from the Disabilities of the Arm, Shoulder and Hand scale (DASH).
  
  
  METHODS
  The 23-item ABILHAND and 30-item DASH were administered to 461 people with MS. Data from the ABILHAND were combined with 16 DASH items to create a 39-item scale (AD-39). Using Rasch Measurement Theory methods, we compared the psychometric properties of AD-39 with ABILHAND.
  
  
  RESULTS
  Data were analysed from 300 people. AD-39 performed robustly as a measure and had greater measurement range, lower floor and ceiling effects, and higher reliability (person separation index 0.97) than ABILHAND. Surprisingly, AD-39 appeared no better than ABILHAND at detecting group differences in self-reported hand function.
  
  
  CONCLUSIONS
  Despite improving some psychometric properties, adding 16 DASH items to the ABILHAND did not improve its measurement performance to the degree expected. Our explanations for this anomaly emphasise the importance of evidence-based, conceptually driven scale modifications guided by hypothesis testing psychometric methods.
authors.affiliation: Clinical Neurology Research Group, Plymouth University Peninsula Schools of Medicine and Dentistry, UK.
authors.forename: Louise
authors.initials: L
authors.lastname: Barrett
authors.affiliation: Clinical Neurology Research Group, Plymouth University Peninsula Schools of Medicine and Dentistry, UK.
authors.forename: Stefan
authors.initials: S
authors.lastname: Cano
authors.affiliation: Clinical Neurology Research Group, Plymouth University Peninsula Schools of Medicine and Dentistry, UK.
authors.forename: John
authors.initials: J
authors.lastname: Zajicek
authors.affiliation: Clinical Neurology Research Group, Plymouth University Peninsula Schools of Medicine and Dentistry, UK Jeremy.Hobart@plymouth.ac.uk.
authors.forename: Jeremy
authors.initials: J
authors.lastname: Hobart
mesh_terms: D000203:Activities of Daily Living; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001132:Arm / Q000503:physiopathology; D004185:Disability Evaluation; D004651:Employment; D005260:Female; D006225:Hand / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009048:Motor Skills; D009068:Movement / Q000502:physiology*; D009103:Multiple Sclerosis / Q000175:diagnosis* / Q000503:physiopathology*; D009460:Neurologic Examination / Q000379:methods*; D011594:Psychometrics; D015203:Reproducibility of Results; D012782:Shoulder / Q000503:physiopathology; D011795:Surveys and Questionnaires; D016896:Treatment Outcome; D055815:Young Adult
keywords: Multiple sclerosis; Rasch Measurement Theory; manual ability; measurement precision; patient-reported outcome measurement; upper limb function