title: Measuring activity limitations in walking: development of a hierarchical scale for patients with lower-extremity disorders who live at home.
abstract: OBJECTIVE
  To develop a hierarchical scale that measures activity limitations in walking in patients with lower-extremity disorders who live at home.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  Orthopedic workshops and outpatient clinics of secondary and tertiary care centers.
  
  
  METHODS
  Patients (N=981; mean age +/- standard deviation, 58.6+/-15.4 y; 46% men) living at home, with different lower-extremity disorders: stroke, poliomyelitis, osteoarthritis, amputation, complex regional pain syndrome type I, and diabetic and degenerative foot disorders.
  
  
  METHODS
  Not applicable.
  
  
  METHODS
  (1) Fit of the monotone homogeneity model, indicating whether items can be used for measuring patients; (2) fit of the double monotonicity model, indicating invariant (hierarchical) item ordering; (3) intratest reliability, indicating repeatability of the sum score; (4) robustness, addressing the clinimetric properties within subgroups of patients; and (5) differential item functioning, addressing the validity of comparisons between subgroups of patients.
  
  
  RESULTS
  Thirty-five of 41 dichotomous items had (1) good fit of the monotone homogeneity model (coefficient H=.50), (2) good fit of the double monotonicity model (coefficient H(T)=.33), (3) good intratest reliability (coefficient rho=.95), (4) satisfactory robustness (within subgroups of patients defined by age, sex, and diagnosis), and (5) some differential item functioning (6 items in amputees compared with nonamputees).
  
  
  CONCLUSIONS
  A hierarchical scale, with excellent scaling characteristics, was developed to measure activity limitations in walking in patients with lower-extremity disorders who live at home. The measurements should be interpreted cautiously when making comparisons between amputees and nonamputees.
authors.affiliation: Department of Rehabilitation Medicine, VU University Medical Center, Amsterdam, The Netherlands. ld.roorda@vumc.nl
authors.forename: Leo D
authors.initials: LD
authors.lastname: Roorda
authors.forename: Marij E
authors.initials: ME
authors.lastname: Roebroeck
authors.forename: Theo
authors.initials: T
authors.lastname: van Tilburg
authors.forename: Ivo W
authors.initials: IW
authors.lastname: Molenaar
authors.forename: Gustaaf J
authors.initials: GJ
authors.lastname: Lankhorst
authors.forename: Lex M
authors.initials: LM
authors.lastname: Bouter
authors.forename: Anne M
authors.initials: AM
authors.lastname: Boonstra
authors.forename: Fred A
authors.initials: FA
authors.lastname: de Laat
authors.forename: Jacob J
authors.initials: JJ
authors.lastname: Caron
authors.forename: Bart J
authors.initials: BJ
authors.lastname: Burger
authors.forename: Ide C
authors.initials: IC
authors.lastname: Heyligers
authors.forename: Frans
authors.initials: F
authors.lastname: Nollet
authors.forename: Irene E
authors.initials: IE
authors.lastname: Stover-Van Herk
authors.forename: Roberto S
authors.initials: RS
authors.lastname: Perez
authors.forename: Jan W
authors.initials: JW
authors.lastname: Meijer
authors.forename: P Mieke
authors.initials: PM
authors.lastname: Rijken
mesh_terms: D003430:Cross-Sectional Studies; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D035002:Lower Extremity; D008297:Male; D008875:Middle Aged; D051346:Mobility Limitation; D009140:Musculoskeletal Diseases / Q000534:rehabilitation*; D009426:Netherlands; D011594:Psychometrics; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires