The classification score is the sum of four domains (0–10 points). Apply it only when there is clinical synovitis in at least one joint and no better alternative diagnosis. A score ≥6 classifies definite rheumatoid arthritis.

Domain	Finding	Points
Joint involvement	1 large joint	0
	2–10 large joints	1
	1–3 small joints	2
	4–10 small joints	3
	>10 joints, including at least 1 small joint	5
Serology	Negative rheumatoid factor and negative anti-CCP	0
	Low-positive rheumatoid factor or anti-CCP	2
	High-positive rheumatoid factor or anti-CCP	3
Acute-phase reactants	Normal CRP and ESR	0
Acute-phase reactants	Abnormal CRP or ESR	1
Symptom duration	<6 weeks	0
Symptom duration	≥6 weeks	1

ACR/EULAR 2010 Rheumatoid Arthritis Classification Criteria