Do self-reported arthritis symptom (RADAR) and health status (AIMS2) data provide duplicative or complementary information?

This study assessed whether self-report measures of symptoms and functional health status provide unique outcome information, or whether functional status assessments primarily serve as a proxy for self-reported arthritis symptoms. Symptom scores of 138 individuals with rheumatoid arthritis (RA) collected with the Rapid Assessment of Disease Activity in Rheumatology (RADAR) measure were compared with same-day functional health scores collected with the recently revised Arthritis Impact Measurement Scales (AIMS2). Correlational and factor analyses revealed that self-assessed arthritis symptoms, physical function and work impact, psychological status, and social health each made independent contributions to outcome. Satisfaction with health status was shown not to be independent of symptoms, functional capacity, or psychological status. It is important to document that self-reported symptom and health status information, when collected concurrently, provides complementary rather than duplicative information.