ACR / EULAR Rheumatoid Arthritis Classification Criteria. These new classification criteria overruled the “old” ACR criteria of 1987 and are adapted for early RA diagnosis. The “new” classification criteria, jointly published by the American College of Rheumatology (ACR) and the European League Against Rheumatism (EULAR) establish a point value between 0 and 10. Every patient with a point total of 6 or higher is unequivocally classified as an RA patient, provided he has synovitis in at least one joint and given that there is no other diagnosis better explaining the synovitis. Four areas are covered in the diagnosis:
joint involvement, designating the metacarpophalangeal joints, proximal interphalangeal joints, the interphalangeal joint of the thumb, second through third metatarsophalangeal joint and wrist as small joints, and elbows, hip joints and knees as large joints:
Involvement of 1 large joint gives 0 points
Involvement of 2-10 large joints gives 1 point
Involvement of 1-3 small joints (with or without involvement of large joints) gives 2 points
Involvement of4-10 small joints (with or without involvement of large joints) gives 3 points
Involvement of more than 10 joints (with involvement of at least 1 small joint) gives 5 points
serological parameters – including the rheumatoid factor as well as ACPA – “ACPA” stands for “anti-citrullinated protein antibody”:
Negative RF and negative ACPA gives 0 points
Low-positive RF or low-positive ACPA gives 2 points
High-positive RF or high-positive ACPA gives 3 points
Signs of destruction and inflammation on magnetic resonance imaging in the second metacarpophalangeal joint in established rheumatoid arthritis. Thin arrows indicate an erosive change; thick arrows indicate synovitis.
Axial T1-weighted magnetic resonance images were obtained (a) before and (b) after contrast administration, also demonstrating synovitis. Additionally, a coronal T1-weighted magnetic resonance image (c) before contrast administration visualizes the same bone erosion as shown in panels a and b.