Appendix 1.

The 1987 American Rheumatism Association (ARA) and 2010 American College of Rheumatology/European League Against Rheumatism (ACR/EULAR) rheumatoid arthritis (RA) classification criteria.

1987 ARA Criteria*2010 ACR/EULAR Criteria
  1. Morning stiffness in and around the joints lasting ≥ 1 hour before maximal improvement

  2. Arthritis of 3 or more joint areas simultaneously with soft tissue swelling or fluid

  3. Arthritis of hand joints with at least 1 area swollen in a wrist, MCP, or PIP joint

  4. Symmetrical arthritis with simultaneous involvement of the same joint areas (as defined in 2)

  5. Rheumatoid nodules

  6. Rheumatoid factor present in abnormal amounts

  7. Radiographic changes typical of RA on hand and wrist radiographs, such as erosions and periarticular osteopenia

*For classification purposes, a patient shall be said to have RA if he/she has satisfied at least 4 of these 7 criteria. Criteria 1 through 4 must have been present for at least 6 weeks. Patients with 2 clinical diagnoses are not excluded. Designation as classic, definite, or probable RA is not to be made.
Target population: Patients who
  1. have at least 1 joint with definite clinical synovitis (swelling)

  2. with the synovitis not better explained by another disease

Classification criteria for RA (score-based) algorithm: add score of categories A–D; a score of ≥ 6/10 is needed for classification of a patient as having definite RA
A. Joint involvement
1 large joint**0
2–10 large joints1
1–3 small joints (with or without large joint involvement***2
4–10 small joints (with or without large joint involvement)3
> 10 joints (≥ 1 small joint)5
B. Serology
Negative RF and negative ACPA0
Low-positive RF or low-positive ACPA2
High-positive RF or high-positive ACPA3
C. Acute-phase reactants
Normal CRP and normal ESR0
Abnormal CRP or abnormal ESR1
D. Duration of symptoms
< 6 weeks0
≥ 6 weeks1
  • ** “Large joints” refers to shoulders, elbows, hips, knees, and ankles.

  • *** “Small joints” refers to metacarpophalangeal (MCP) joints, proximal interphalangeal (PIP) joints, second through fifth metatarsophalangeal joints, thumb interphalangeal joints, and wrists. RF: rheumatoid factor; ESR: erythrocyte sedimentation rate; CRP: C-reactive protein; ACPA: anticitrullinated protein antibodies.