Is juvenile rheumatoid arthritis/juvenile idiopathic arthritis different from rheumatoid arthritis?

Table 1 Similarities and differences between RA and JRA/JIA

Feature	RA	JRA/JIA
Classification criteria	Single disease with different manifestations	Phenotypically and genetically distinct subtypes
Gender	Females > males	Females > males except in systemic arthritis
Age of onset	Puberty plus; peak 4th to 5th decade	Polyarticular: throughout childhood; peak 1-3 years of age
		Pauciarticular: early childhood; peak 1-2 years of age
		Systemic: throughout childhood; no peak
Extended multiplex families	Present	Very rare
Family history of other autoimmune disorders	Present	Present
Typical ocular involvement	Keratoconjunctivitis sicca	Chronic anterior uveitis
Prevalence	10/1000	0.86/1000
Ethnic distribution	Reported in all populations	EOPA is rare in non-Caucasians
HLA association	HLA DRB10401, 0404, 0101* in Caucasians	EOPA: HLA-A2, -DR5, -DR8, -DPB10201*. (HLA-DR4 is protective)
		Late pauciarticular: HLA-B27
		Polyarticular: HLA-DR1, -DR4
Shared epitope	Defined; amino acid positions 67-74 of third hypervariable region	Not described
Growth/developmental issues	Rare	Common
Pathophysiology	Th1-mediated disease	Th1-mediated disease (Pauciarticular: Also Th2-mediated)
Autoantibodies	IgM RF common	IgM RF rare
Natural history	Majority have long-term disability	Fewer than half have long-term disability

EOPA, early-onset pauciarticular arthritis; HLA, human leukocyte antigen; JIA, juvenile idiopathic arthritis; JRA, juvenile rheumatoid arthritis; RA, rheumatoid arthritis; RF, rheumatoid factor; Th, T helper.

ISSN: 1478-6362