No 12, 2012

Publication of the Month

 

 

December 12/12: 

anti-CCP in juvenile idiopathic arthritis    

 

Key messages:

  • Anti-CCP antibodies occur  in 14% of children with juvenile idiopathic arthritis (JIA)
  • CCP testing should be included in the classification of JIA to determine a distinct JIA phenotype    

Tebo AE, Jaskowski TD, Davis WK, Whiting A, Clifford B, Zeft AS, McNally B, Hill HR, Bohnsack JF, Prahalad S
Profiling anti-cyclic citrullinated peptide antibodies in patients with juvenile idiopathic arthritis Pediatr.
Rheumatol. 2012;10:29-34  

 

Background:
Juvenile idiopathic arthritis (JIA) is the most common cause of chronic arthritis in children. Some cases phenotypically resemble RA with polyarthritis and test positive for rheumatoid factor (RF). This study investigates the prevalence of cyclic citrullinated peptide antibodies (anti-CCP) and its relationship to other serological markers associated with RA in a cohort of 334 children with JIA.  

Summary:

  All JIA
n = 334
Systemic
n = 31
Polyarticular, RF+
n = 30
Polyarticular, RF-
n = 76
Persistent oligoarticular
n = 119
Extended oligoarticular
n = 26
Undifferentiated arthritis
n = 25
CCP 48 (14%) 4 (13%) 22 (73%) 6 (8%) 5 (4%) 5 (19%) 5 (20%)
RF IgM 40 (12%) 1 (3%) 28 (93%) 1 (1%) 2 (2%) 0 24 (6%)

Table: prevalence of anti-CCP and RF IgM in the different subtypes of JIA.  

4 of the 50 healthy controls were positive for RF IgM and 1 healthy child had anti-CCP antibodies. 25 JIA cases were positive for both RF IgM and anti-CCP, while 23 anti-CCP positive cases had no RF IgM. Children negative for RF IgM but positive for anti-CCP differed from those who were positive for both RF IgM and anti-CCP by having an earlier onset-age, fewer HLA-DRB1 shared epitope alleles, and lower titres of anti-CCP. Prevalence of anti-RA33 was not different between cases and controls.  

Conclusions:
Children with positive anti-CCP but negative RF are frequent and may define a distinct subset of children with JIA. Therefore anti-CCP testing should be included in the classification of JIA.  

Comment:
Although this study might have some pitfalls such as the low number of controls (50 healthy children), it shows that it is useful to include anti-CCP in the classification of juvenile idiopathic arthritis as this might help in the determination of the distinct JIA phenotypes and therefore in prognosis.

 

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As in all diagnostic testing, the diagnosis is made by the physican based on both test results and the patient history.