Measuring activity limitations in walking: development of a hierarchical scale for patients with lower-extremity disorders who live at home.
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.
Roorda
Leo D
LD
Department of Rehabilitation Medicine, VU University Medical Center, Amsterdam, The Netherlands. ld.roorda@vumc.nl
Roebroeck
Marij E
ME
van Tilburg
Theo
T
Molenaar
Ivo W
IW
Lankhorst
Gustaaf J
GJ
Bouter
Lex M
LM
Boonstra
Anne M
AM
de Laat
Fred A
FA
Caron
Jacob J
JJ
Burger
Bart J
BJ
Heyligers
Ide C
IC
Nollet
Frans
F
Stover-Van Herk
Irene E
IE
Perez
Roberto S
RS
Meijer
Jan W
JW
Rijken
P Mieke
PM
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