A multicenter international study on the Spinal Cord Independence Measure, version III: Rasch psychometric validation.
BACKGROUND
A third version of the Spinal Cord Independence Measure (SCIM III), made up of three subscales, was formulated following comments by experts from several countries and Rasch analysis performed on the previous version.


OBJECTIVE
To examine the validity, reliability, and usefulness of SCIM III using Rasch analysis.


METHODS
Multicenter cohort study.


METHODS
Thirteen spinal cord units in six countries from North America, Europe, and the Middle-East.


METHODS
425 patients with spinal cord lesions (SCL).


METHODS
SCIM III assessments by professional staff members. Rasch analysis of admission scores.


METHODS
SCIM III subscale match between the distribution of item difficulty grades and the patient ability measurements; reliability of patient ability measures; fit of data to Rasch model requirements; unidimensionality of each subscale; hierarchical ordering of categories within items; differential item functioning across classes of patients and across countries.


RESULTS
Results supported the compatibility of the SCIM subscales with the stringent Rasch requirements. Average infit mean-square indices were 0.79-1.06; statistically distinct strata of abilities were 3 to 4; most thresholds between adjacent categories were properly ordered; item hierarchy was stable across most of the clinical subgroups and across countries. In a few items, however, misfit or category threshold disordering were found.


CONCLUSIONS
The scores of each SCIM III subscale appear as a reliable and useful quantitative representation of a specific construct of independence after SCL. This justifies the use of SCIM in clinical research, including cross-cultural trials. The results also suggest that there is merit in further refining the scale.
Catz
A
A
Spinal Department, Loewenstein Rehabilitation Hospital, Raanana, Israel.
Itzkovich
M
M
Tesio
L
L
Biering-Sorensen
F
F
Weeks
C
C
Laramee
M T
MT
Craven
B C
BC
Tonack
M
M
Hitzig
S L
SL
Glaser
E
E
Zeilig
G
G
Aito
S
S
Scivoletto
G
G
Mecci
M
M
Chadwick
R J
RJ
El Masry
W S
WS
Osman
A
A
Glass
C A
CA
Silva
P
P
Soni
B M
BM
Gardner
B P
BP
Savic
G
G
Bergström
E M
EM
Bluvshtein
V
V
Ronen
J
J
D000203:Activities of Daily Living; D000328:Adult; D015331:Cohort Studies; D004185:Disability Evaluation; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D011594:Psychometrics / Q000379:methods*; D015203:Reproducibility of Results; D012984:Software; D013119:Spinal Cord Injuries / Q000503:physiopathology*; D011795:Surveys and Questionnaires