WOMAC osteoarthritis index. Reliability, validity, and responsiveness in patients with arthroscopically assessed osteoarthritis. Western Ontario and MacMaster Universities.
OBJECTIVE
To validate the WOMAC Osteoarthritis Index for use in Sweden.


METHODS
Test-retest reliability, internal consistency, validity, and responsiveness was determined in 52 patients (mean age 48 (20-69)) with arthroscopically assessed cartilage damage of the tibio-femoral knee joint.


RESULTS
All WOMAC scales were internally consistent with Cronbach's alpha coefficients of 0.83, 0.87, and 0.96 pre-operatively. Test-retest reliability was satisfactory with intraclass correlation coefficients of 0.74, 0.58, and 0.92. As hypothesized worse post-operative but not pre-operative outcomes were associated with radiographic OA. In comparison with the SF-36 the expected correlations were found when comparing items measuring similar and dissimilar constructs, supporting the concepts of convergent and divergent construct validity. Three months after arthroscopy significant mean improvement was seen in all WOMAC scales (p<0.0004).


CONCLUSIONS
The Swedish version of WOMAC is a reliable, valid, and responsive instrument with metric properties in agreement with the original widely used version.
Roos
E M
EM
Institute of Musculoskeletal Disease, Department of Physical Therapy, Lund University, Sweden.
Klässbo
M
M
Lohmander
L S
LS
D000328:Adult; D000368:Aged; D001182:Arthroscopy; D002358:Cartilage, Articular / Q000000981:diagnostic imaging / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000175:diagnosis* / Q000503:physiopathology* / Q000601:surgery; D010146:Pain; D011859:Radiography; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires; D013548:Sweden