A comparison of four indirect methods of assessing utility values in rheumatoid arthritis.
OBJECTIVE
Utility scores can be assessed indirectly using preference-based instruments and used as weightings for quality-adjusted life years in economic analyses. It is not clear whether available instruments yield similar results or what domains of health are contributing to the overall score in a sample of patients with rheumatoid arthritis (RA).


METHODS
Our study included 313 individuals with rheumatologist-confirmed RA.


METHODS
A self-completed survey that permitted scoring of 4 indirect utility instruments (the Health Utilities Index Mark 2 and 3 (HUI-2 and HUI-3), the EuroQoL (EQ-5D), and the Short Form 6D (SF-6D) was the basis of our study.


RESULTS
Mean (standard deviation) global utility scores were 0.63 (0.24) for the SF-6D, 0.66 (0.13) for the EQ-5D, 0.71 (0.19) for the HUI-2, and 0.53 (0.29) for the HUI-3 (P = 0.02 by repeated-measures analysis of variance). The intraclass correlation across all the indices was 0.67 (95% confidence interval 0.62-0.71). Bland-Altman plots revealed that agreement among instruments was poor at lower utility values. In this elderly RA sample, all of the global utilities mostly measured functional ability and pain.


CONCLUSIONS
There are significant differences in utilities obtained from different indirect methods. Agreement among the instruments was moderate but poorer at lower utilities. It is unlikely that these utility values, if used as the weightings for quality-adjusted life years, would result in comparable estimates.
Marra
Carlo A
CA
Department of Health Care and Epidemiology, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada.
Esdaile
John M
JM
Guh
Daphne
D
Kopec
Jacek A
JA
Brazier
John E
JE
Koehler
Barry E
BE
Chalmers
Andrew
A
Anis
Aslam H
AH
D000203:Activities of Daily Living; D001172:Arthritis, Rheumatoid / Q000453:epidemiology* / Q000503:physiopathology / Q000523:psychology; D001955:British Columbia / Q000453:epidemiology; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D008297:Male; D008603:Mental Health / Q000706:statistics & numerical data; D008875:Middle Aged; D011159:Population Surveillance; D011788:Quality of Life; D019057:Quality-Adjusted Life Years; D012044:Regression Analysis; D018434:Sickness Impact Profile