How do symptoms of each joint contribute to global pain, disease activity and functional disability in rheumatoid arthritis? -a comprehensive association study using a large cohort

Background: Established assessment tools for patients with rheumatoid arthritis (RA), including disease activity scores (DASs), disease activity indices (DAIs), visual analog scales (VASs), and health assessment questionnaires (HAQs), are widely used. However, comparative associations between joint involvement and disease status assessment tools have rarely been investigated. Methods: : We included a dataset of 4016 patients from a large RA cohort from 2012 to 2019. The tenderness and swelling of each joint were counted as a symptom, with 70 and 68 affected joints throughout the body, respectively. The relative contribution of various joints to the disease status assessment tools, VAS scores, and functional disability indexes was analyzed using multiple regression analysis. Results: : Upper extremity joints contributed more than the lower extremity joints, except the knee, toward disease assessment. Additionally, larger joints contributed more than the smaller joints overall, but the metacarpophalangeal and proximal interphalangeal joints made significant contributions to DASs and DAIs. Further, the ankle played a minor but important role in most assessment tools, especially in HAQs. Conclusions: : Larger joints and the joints in the upper extremity contribute more to disease status, VAS score, and functional disability. However, each joint makes a unique contribution to these assessment tools.