Objective: To determine how well self-report functional ability reflects the impairment due to the arthritic process in rheumatoid arthritis (RA) and how much it is affected by other factors of health status.
Methods: We examined the relationships between self-report measures such as the Health Assessment Questionnaire (HAQ) and Arthritis Impact Measurement Scales (AIMS) and measures of impairment such as the Keitel function test (KFT), which is intended to reflect the degree of functional limitation of the joints, grip strength and radiological destruction as well as anxiety and depression in a population-based series of RA.
Results: First, the HAQ and AIMS had a high correlation coefficient (r = 0.89, p < 0.0001). Second, the above measures of impairment were more significant predictors of self-report functional measures than, for example, mental health perceptions. The AIMS scales also correlated well with the corresponding physical function of the KFT.
Conclusion: Patients' self-report functional ability in RA reflects their physical impairment due to the arthritic joint disease and is less influenced by other factors such as emotional adjustment.