The computerized analysis of 262 patients who were evaluated consecutively formed a basis for the revised classification of rheumatoid arthritis (RA). It also included 262 other patients suffering from rheumatic diseases apart from RA (non-RA).
The new criteria of classification included: 1. Swollen soft tissue (arthritis), 2. Stiffness of joints in the morning, 3. Swollen proximal interphalangeal or inflammation of wrist joints, 5. Signs of rheumatoid factor, 6. Rheumatoid nodules, and 7. Radiographic erosions or periarticular osteopenia. The stages 1 to 6 continued for over 6 weeks. The RA condition is defined when the 4 or more criteria are noticed and this does not require further classification or exclusion. Besides, a “classification tree” schema is included which is as important as the traditional (4-7) format.
From the new criteria of RA classification, 89% specificity and 91-94% sensitivity were demonstrated on being compared to non-rheumatic disease control patients.