Table 2. Reported prevalence of RF in many conditions

Autoimmune rheumatic diseases	%
Rheumatoid arthritis (RA)	60–70
Early undifferentiated arthritis	45–55
Juvenile idiopathic arthritis (JIA)	2–12
SLE	14–30
Sjögren syndrome (SjS)	46–85
Systemic sclerosis (SSc)	20–30
IIM (e.g., DM/PM)	5–10
Granulomatosis with polyangiitis (GPA)	~50

Infectious diseases	%
Endocarditis	15–20
Hepatitis B/C	15–40
Leprosy	10–50
Tuberculosis	10–20
Epstein-Barr virus	~20

Healthy subjects	%
Adults	4–20
Children	3–8

RF: rheumatoid factor; SLE: systemic lupus erythematosus; IIM: idiopathic inflammatory myopathy; DM/PM: dermatomyositis/polymyositis.