title: Measuring upper limb capacity in poststroke patients: development, fit of the monotone homogeneity model, unidimensionality, fit of the double monotonicity model, differential item functioning, internal consistency, and feasibility of the stroke upper limb capacity scale, SULCS.
abstract: OBJECTIVE
  To develop an easy-to-use scale that measures upper limb capacity, according to the International Classification of Functioning, Disability and Health definition, in patients after stroke, and to investigate certain psychometric properties of this scale.
  
  
  METHODS
  Cohort study.
  
  
  METHODS
  Inpatient department of a rehabilitation center.
  
  
  METHODS
  Patients (N=546; mean age ± SD, 60.1±11.2y; 56% men) undergoing rehabilitation after stroke.
  
  
  METHODS
  Not applicable.
  
  
  METHODS
  Mokken scale analysis was used to investigate the following psychometric properties: (1) fit of the monotone homogeneity model, indicating that the items form a scale; (2) unidimensionality, indicating that the items measure only 1 concept (or construct); (3) fit of the double monotonicity model, indicating invariant (hierarchical) item ordering; (4) differential item functioning (DIF), indicating the validity of comparison between subgroups; and (5) internal consistency, indicating the degree of interrelatedness of the items. The mean time needed to complete the scale was calculated to indicate (6) feasibility.
  
  
  RESULTS
  The Stroke Upper Limb Capacity Scale (SULCS) was developed on the basis of interviews with experts. Ten of 15 items had (1) good fit of the monotone homogeneity model (coefficient H=.88), were (2) unidimensional, and had (3) good fit of the double monotonicity model (coefficient H(T)=.71), (4) absence of DIF (Crit-values <40), and (5) good internal consistency (coefficient ρ=.96). When applying start-and-stop rules, the (6) feasibility of the SULCS was good (6min).
  
  
  CONCLUSIONS
  The SULCS is an easy-to-use, unidimensional, hierarchical, and internally consistent scale that assesses upper limb capacity in patients after stroke.
authors.affiliation: Department of Rehabilitation, Nijmegen Centre for Evidence Based Practice, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands. l.roorda@reade.nl
authors.forename: Leo D
authors.initials: LD
authors.lastname: Roorda
authors.forename: Annemieke
authors.initials: A
authors.lastname: Houwink
authors.forename: Wendy
authors.initials: W
authors.lastname: Smits
authors.forename: Ivo W
authors.initials: IW
authors.lastname: Molenaar
authors.forename: Alexander C
authors.initials: AC
authors.lastname: Geurts
mesh_terms: D016009:Chi-Square Distribution; D015331:Cohort Studies; D004185:Disability Evaluation; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D038801:International Classification of Diseases; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D011594:Psychometrics; D020521:Stroke / Q000503:physiopathology*; D000071939:Stroke Rehabilitation; D034941:Upper Extremity / Q000503:physiopathology*