The clinimetric properties of the World Health Organization Disability Assessment Schedule II in early inflammatory arthritis.
OBJECTIVE
To assess the clinimetric properties of a new health-related quality of life (HRQOL) instrument, the World Health Organization Disability Assessment Schedule II (WHODAS II), in patients with early inflammatory arthritis.


METHODS
Internal consistency as well as criterion, construct, and discriminative validity of the WHODAS II were assessed in 172 patients with early inflammatory arthritis who completed the WHODAS II, the Medical Outcomes Study Short Form 36 (SF-36), and other measures of disease severity, functioning, pain, depression, and resource use. Test-retest reliability of the WHODAS II was assessed by having a subset of 20 patients complete the WHODAS II a second time, 1 week after the first assessment.


RESULTS
The WHODAS II had high internal consistency (Cronbach's alpha = 0.96 for patients working or in school and 0.93 for patients not working or in school). Test-retest intraclass correlation coefficients of the WHODAS II total score and subscales ranged from 0.82-0.96. The WHODAS II total score was strongly correlated with the SF-36 physical component score (Kendall's tau-b 0.51, P < 0.001) and moderately correlated with the SF-36 mental component score (tau-b 0.43, P < 0.001). WHODAS II correlations with disease outcomes ranged from Kendall's tau-b 0.15-0.55. The WHODAS II significantly differentiated between every aspect of disease severity assessed with the exception of measures of health resource use.


CONCLUSIONS
The WHODAS II is a valid and reliable measure of HRQOL in cross-sectional studies of patients with early inflammatory arthritis. Research is still required to investigate potential item redundancy and determine its usefulness in longitudinal studies.
Baron
Murray
M
McGill University, Montreal, Quebec, Canada. mbaron@rhu.jgh.mcgill.ca
Schieir
Orit
O
Hudson
Marie
M
Steele
Russell
R
Kolahi
Sousan
S
Berkson
Laeora
L
Couture
Francois
F
Fitzcharles
M A
MA
Gagné
Michel
M
Garfield
Bruce
B
Gutkowski
Andrzej
A
Kang
Harb
H
Kapusta
Morton
M
Ligier
Sophie
S
Mathieu
Jean-Pierre
JP
Ménard
Henri
H
Starr
Michael
M
Stein
Michael
M
Zummer
Michel
M
D000203:Activities of Daily Living; D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000150:complications*; D003430:Cross-Sectional Studies; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011788:Quality of Life; D012720:Severity of Illness Index; D014944:World Health Organization