Measuring activity limitations in climbing stairs: development of a hierarchical scale for patients with lower-extremity disorders living at home.
OBJECTIVE
To develop a hierarchical scale that measures activity limitations in climbing stairs in patients with lower-extremity disorders living at home.


METHODS
Cross-sectional study with Mokken scale analysis of 15 dichotomous items.


METHODS
Outpatient clinics of secondary and tertiary care centers.


METHODS
Patients (N=759; mean age +/- standard deviation, 59.8+/-15.0y; 48% men) living at home, with different lower-extremity disorders: stroke, poliomyelitis, osteoarthritis, amputation, complex regional pain syndrome type I, and diabetic foot problems.


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; and (4) differential item functioning, addressing the validity of comparisons between subgroups of patients.


RESULTS
There was (1) good fit of the monotone homogeneity model (coefficient H=.50) for all items for all patients, and for subgroups defined by age, gender, and diagnosis; (2) good fit of the double monotonicity model (coefficient H(T)=.58); (3) good intratest reliability (coefficient rho=.90); and (4) no differential item functioning with respect to age and gender, but differential item functioning for 4 items in amputees compared with nonamputees.


CONCLUSIONS
A hierarchical scale, with excellent scaling characteristics, has been developed for measuring activity limitations in climbing stairs in patients with lower-extremity disorders who live at home. However, measurements should be interpreted with caution when comparisons are made between patients with and without amputation.
Roorda
Leo D
LD
Department of Rehabilitation, VU University Medical Center, PO Box 7057, 1007 MB Amsterdam, The Netherlands. ld.roorda@vumc.nl
Roebroeck
Marij E
ME
van Tilburg
Theo
T
Lankhorst
Gustaaf J
GJ
Bouter
Lex M
LM
D000203:Activities of Daily Living; D000674:Amputees; D003430:Cross-Sectional Studies; D017719:Diabetic Foot / Q000503:physiopathology; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D035002:Lower Extremity / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D010003:Osteoarthritis / Q000503:physiopathology; D011051:Poliomyelitis / Q000503:physiopathology; D020521:Stroke / Q000503:physiopathology