title: Psychometric validation of a patient-reported measure of physical functioning in sporadic inclusion body myositis.
abstract: To assess self-reported physical functioning in patients with sporadic inclusion body myositis (sIBM), the sIBM Physical Functioning Assessment (sIFA) was developed. This research establishes the validity, reliability, and responsiveness of the sIFA in patients with sIBM.
  
  
  
  Data from 3 small, noninterventional, observational studies were analyzed. Several measures of physical function were included to assess validity. Reliability (Cronbach alpha, test-retest intraclass correlations), construct validity (correlations, analyses of variance), and responsiveness (effect size estimates) were evaluated.
  
  
  
  Cronbach alphas (range = 0.86-0.91) and test-retest reliability (0.91) were highly satisfactory. Correlations with other measures provided evidence of convergent validity. sIBM patients able to walk without assistive devices scored significantly better on the sIFA (means = 36.0-47.05) than those who required power mobility or wheelchairs (means = 54.9-71.5), demonstrating the discriminating ability of the sIFA. Effect size estimates of responsiveness suggested mild functional progression.
  
  
  
  Psychometric analyses of the sIFA demonstrate satisfactory reliability, validity, and responsiveness. Muscle Nerve 54: 658-665, 2016.
authors.affiliation: RTI Health Solutions, 200 Park Offices Drive, Research Triangle Park, North Carolina, 27709, USA. vwilliams@rti.org.
authors.forename: Valerie
authors.initials: V
authors.lastname: Williams
authors.affiliation: RTI Health Solutions, 200 Park Offices Drive, Research Triangle Park, North Carolina, 27709, USA.
authors.forename: Theresa
authors.initials: T
authors.lastname: Coles
authors.affiliation: RTI Health Solutions, 200 Park Offices Drive, Research Triangle Park, North Carolina, 27709, USA.
authors.forename: Ari
authors.initials: A
authors.lastname: Gnanasakthy
authors.affiliation: RTI Health Solutions, 200 Park Offices Drive, Research Triangle Park, North Carolina, 27709, USA.
authors.forename: Carla
authors.initials: C
authors.lastname: Demuro
authors.affiliation: RTI Health Solutions, 200 Park Offices Drive, Research Triangle Park, North Carolina, 27709, USA.
authors.forename: Stuart
authors.initials: S
authors.lastname: Yarr
authors.affiliation: RTI Health Solutions, 200 Park Offices Drive, Research Triangle Park, North Carolina, 27709, USA.
authors.forename: Nicole
authors.initials: N
authors.lastname: Williams
authors.affiliation: Nationwide Children's Hospital, Columbus, Ohio, USA.
authors.forename: Linda
authors.initials: L
authors.lastname: Lowes
authors.affiliation: Nationwide Children's Hospital, Columbus, Ohio, USA.
authors.forename: Lindsay
authors.initials: L
authors.lastname: Alfano
authors.affiliation: Novartis Pharmaceuticals, East Hanover, New Jersey, USA.
authors.forename: Brian
authors.initials: B
authors.lastname: Tseng
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018979:Myositis, Inclusion Body / Q000175:diagnosis* / Q000503:physiopathology; D011594:Psychometrics; D015203:Reproducibility of Results; D057566:Self Report / Q000592:standards*; D011795:Surveys and Questionnaires / Q000592:standards*
keywords: patient-reported outcomes; physical functioning; psychometric evaluation; sporadic inclusion body myositis; validation