Confirmatory factor analysis of 12-Item World Health Organization Disability Assessment Schedule in patients with musculoskeletal pain conditions.
OBJECTIVE
To investigate the factor structure of the 12 item World Health Organization Disability Assessment Schedule (WHODAS) 2.0.


METHODS
Cross-sectional cohort survey study.


METHODS
Physical and Rehabilitation Medicine outpatient university clinic.


METHODS
The 408 consecutive patients with chronic musculoskeletal pain.


METHODS
Exploratory and confirmatory factor analysis.


RESULTS
A two-factor model most accurately fit the observed data of musculoskeletal pain patients (root mean square error of approximation 0.049, relative Chi square value 1.99). Twelve WHODAS 2.0 items were distributed between two factors with covariance between them of 0.8. The first factor contained domains related mostly to physical functioning, while another was associated mostly with social and cognitive functioning. There were a few differences between single items in their importance in defining the variance within these two factors. Of the six International Classification of Functioning, Disability and Health domains belonging to the first construct, the ability to carry out household responsibilities explained most, 84% of the total variance in this construct. For the second factor, the ability to participate in community activities seemed to be the most important, explaining 85% of the total variance in this construct.


CONCLUSIONS
In this study, the two-factor structure model of the 12-item WODAS 2.0 demonstrated the most accurate fit within patients with musculoskeletal pain conditions.
1 Department of Physical and Rehabilitation Medicine, Turku University Hospital and University of Turku, Turku, Finland.
Mikhail
M
Saltychev
2 Department of Orthopedic Surgery, Stanford University Hospital & Clinics, Stanford, CA, USA.
Ryan
R
Mattie
3 Department of Physical Medicine and Rehabilitation, The Rehabilitation Institute of Chicago/Northwestern McGaw Medical Center, Chicago, IL, USA.
Zachary
Z
McCormick
1 Department of Physical and Rehabilitation Medicine, Turku University Hospital and University of Turku, Turku, Finland.
Katri
K
Laimi
D000203:Activities of Daily Living; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016009:Chi-Square Distribution; D059350:Chronic Pain / Q000503:physiopathology; D003430:Cross-Sectional Studies; D004185:Disability Evaluation; D006233:Persons with Disabilities / Q000523:psychology*; D005163:Factor Analysis, Statistical; D005260:Female; D005387:Finland; D006801:Humans; D064702:International Classification of Functioning, Disability and Health; D008297:Male; D008875:Middle Aged; D059352:Musculoskeletal Pain / Q000503:physiopathology*; D010045:Outpatients; D011594:Psychometrics; D011788:Quality of Life / Q000523:psychology*; D012047:Rehabilitation Centers; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires; D014944:World Health Organization; D055815:Young Adult
Disability and Health; Functioning; International Classification of Functioning; WHODAS; disability; factor analysis; psychometric