Article

OBJECTIVE: To determine the validity of 15 standardized instruments frequently
used to measure the outcome of chronic arthritis treatment. METHODS: Analyses
were performed on data collected at a rehabilitation programme (n=216). The
outcome measures evaluated were health-related quality of life, global health,
pain, physical function and aerobic capacity. The instrument items were linked to
the International Classification of Functioning, Disability and Health (ICF)
(content validity), construct validity was analysed based on predetermined
hypothesis (Spearman's correlations, rs), and responsiveness (after 18 days and
12 months) by the standardized response mean. RESULTS: Most instruments covered
the ICF component body function and/or activity-participation, only a few covered
the environmental component. The short Euroqol-5 Dimensions performed as well as
the longer health-related quality of life instruments in covering the ICF and in
responsiveness. The health-related quality of life instruments did not measure
similar constructs as hypothesized, neither did pain measures. The Bath
Ankylosing Spondylitis indices covered several components of the ICF often
exhibiting a large responsiveness. Aerobic capacity had the largest
responsiveness of all measures. CONCLUSION: Many instruments are not highly
correlated, although at face value they appear to measure the same construct,
information also applying to content validity and responsiveness. Results from
this study can assist in choosing outcome measures in the clinic and in research.

Langue : ANGLAIS