Rheumatoid Arthritis Prediction Rule for Undifferentiated Arthritis

1. Indications
   1. Rheumatoid Arthritis Diagnosis
2. Criteria
   1. Points clc: Age (calculated points = AgeYrs * 0.02)
   2. Points 1.0: Female Gender
   3. Points 0.5: Small joints of hands or feet affected
   4. Points 0.5: Symmetric joints involved
   5. Points 1.0: Upper extremities affected
   6. Points 1.5: Upper and lowe extremities affected
   7. Points 1.0: Morning stiffness rated at 26-90 mm on a 100 mm visual analog scale
   8. Points 2.0: Morning stiffness rated at >90 mm on a 100 mm visual analog scale
   9. Points 0.5: Number of tender joints 4-10
   10. Points 1.0: Number of tender joints 11 or more
   11. Points 0.5: Number of swollen joints 4-10
   12. Points 1.0: Number of swollen joints 11 or more
   13. Points 0.5: C-Reactive Protein 5 to 50 mg/L
   14. Points 1.5: C-Reactive Protein >51 mg/L
   15. Points 1.0: Rheumatoid Factor positive
   16. Points 2.0: Anti-Citrullinated Protein Antibody positive
3. Interpretation: Based on total cummulative score tallied from above criteria
   1. Score 0.0 - 3.5: Percentage with RA at one year 0% (LR 0)
   2. Score 3.5 - 6.5: Percentage with RA at one year 16% (LR 0.4)
   3. Score 6.5 - 8.5: Percentage with RA at one year 57% (LR 3.0)
   4. Score over 8.5: Percentage with RA at one year 85% (LR 12.7)
4. References
   1. van der Helm-van Mil (2007) Arthritis Rheum 56(2): 433-40
   2. Mochan (2008) Am Fam Physician 77(10): 1451-3