@article {Brooks1180, author = {Lyndon O Brooks and Margaret I Rolfe and Phillip A Cheras and Stephen P Myers}, title = {The comprehensive osteoarthritis test: a simple index for measurement of treatment effects in clinical trials.}, volume = {31}, number = {6}, pages = {1180--1186}, year = {2004}, publisher = {The Journal of Rheumatology}, abstract = {OBJECTIVE: To assess the measurement properties of a simple index of symptom severity in osteoarthritis (OA) of the hips and knees. METHODS: Both the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and the proposed new Comprehensive Osteoarthritis Test (COAT) instrument were completed weekly by 125 subjects in the context of a randomized, 12-week, 3 parallel-arm clinical trial. The reliabilities of the various scales were assessed on a weekly basis by use of Cronbach{\textquoteright}s alpha coefficients. The validity of the COAT total scale was assessed by correlation with the WOMAC total scale on a weekly basis with correlation coefficients, and in terms of the correlations between subject-level intercepts and slopes over time. The relative responsiveness of the WOMAC and COAT total scales was assessed using a multilevel (longitudinal) multivariate (WOMAC, COAT) linear model. RESULTS: The WOMAC and COAT total scales were highly reliable (mean over weeks: WOMAC alpha = 0.98; COAT alpha = 0.97). The correlations between the WOMAC and COAT scales were very high (mean over weeks = 0.92; subject-level intercepts = 0.91, slopes = 0.88). The COAT total scale was significantly more responsive than the WOMAC total scale in the active treatment (34.8\% improvement vs 26.8\%; p = 0.002). CONCLUSION: The COAT total scale is simple to administer, reliable, valid, and responsive to treatment effects.}, issn = {0315-162X}, URL = {https://www.jrheum.org/content/31/6/1180}, eprint = {https://www.jrheum.org/content/31/6/1180.full.pdf}, journal = {The Journal of Rheumatology} }