Objective: To examine the relationship of the Arthritis Impact Measurement Scales (AIMS) to changes in articular status and functional performance in a group of patients with psoriatic arthritis (PsA).
Methods: The AIMS was administered to 65 patients attending the University of Toronto Psoriatic Arthritis Clinic in 1989 and in 1993. Clinical and laboratory assessments of function, active inflammation, and damage were also performed at these 2 clinic visits. Linear regression analysis was performed to relate changes in the number of actively inflamed joints and number of deformed joints to AIMS measurements, while logistic regression was used to relate the American College of Rheumatology (ACR) functional class and the AIMS scores taken at the 2 clinic visits.
Results: There were 27 women and 38 men with a mean age of 46 years and arthritis duration of 13 years. Based only on information derived from the AIMS questionnaire, the maximum percentage of variation explained was 21 and 9% for the number of active joints and deformed joints, respectively. The strongest relationship was between the pain component scales measured at the 2 visits and the number of active joints. In all cases the initial clinical value made a significant additional contribution to the regression.
Conclusion: The finding that the AIMS was sensitive to articular changes that occurred in patients over a 4 year period provides further support for the utility of the AIMS as an outcome measure in clinical studies of PsA. However, changes in the AIMS did not capture the full extent of the changes in both articular status and ACR functional class. This suggests that the AIMS and traditional measures of disease activity and function assess somewhat different aspects of clinical status and that it may be beneficial to use both types of measures in monitoring the course of PsA.