New Provisional Classification of Juvenile Idiopathic Arthritis Applying Rheumatoid Factor and Antinuclear Antibody

Abstract

Objective. Previous classification systems for juvenile idiopathic arthritis (JIA) were based on the number of joints involved and did not categorize homogenous disease entities. Therefore, JIA patients were reclassified retrospectively by applying rheumatoid factor (RF) and antinuclear antibody (ANA), which have been proven to constitute a homogenous disease entity. Methods. The medical records of JIA patients were investigated retrospectively and reclassified into six categories using the new provisional classification. The nomenclature was based on Dr. Martini's proposal in the 23rd European Paediatric Rheumatology Congress (2016) at Genoa, Italy. New categories included systemic JIA (sJIA), RF-positive JIA (RF-JIA), early-onset ANA-positive JIA (eoANA-JIA), enthesitis/spondylitis-related JIA (ESR-JIA), "other JIA", and "unclassified JIA". Results. Of a total of 262 JIA patients, 71 (27.1%) were reclassified as sJIA, 31 (11.8%) as RF-JIA, 22 (8.4%) as eoANA-JIA, 63 (24.0%) as ESR-JIA, 65 (24.8%) as "other JIA", and 10 (3.8%) as "unclassified JIA". A comparison of RF-JIA, eoANA-JIA, and ESR-JIA revealed significant differences in the gender ratio, age of disease onset, and the cumulative number and type of joints involved among the three groups. "Other JIA" comprised a significant proportion (24.8%) and warrants the need for further classification. The characteristics of the RF-positive patients were comparable to those of the anti-cyclic citrullinated peptide antibody-positive patients. The ANA positivity was lower (28.2%) than that in Western studies but showed similar clinical features. Conclusion. This is the first study applying RF and ANA to classify JIA without considering the joint counts. The six new categories include sJIA, RF-JIA, eoANA-JIA, ESR-JIA, "other JIA," and "unclassified JIA". (J Rheum Dis 2018;25:34-46)

Clinical Features and Risk Factors of Uveitis in Korean Children with Juvenile Idiopathic Arthritis

“…The patients were considered ANApositive if they had at least two positive results on indirect immuno uorescence assay performed over 3 months apart. 10,12 HEp-2 cells were the substrate used for ANA determination. The patients were considered RF-positive if they had at least two positive results (≥ 20 IU/mL) for over 3 months apart.…”

Newly Proposed Classification for Juvenile Idiopathic Arthritis

“…In a previous issue of this journal, Kwon et al [9] proposed that JIA patients should be reclassified according to RF and ANA to identify homogeneous disease entities, while the number of involved joints and the presence of psoriasis were recommended to be excluded from the ILAR classification. The medical records of 262 JIA patients were investigated retrospectively and the patients were reclassified into six categories using the new classification system proposed by Martini at the 23rd Paediatric Rheumatology European Society Congress (2016) [9].…”

“…However, 24.8% of the patients did not meet the criteria for one of these four categories and were reclassified as other JIA, which is not a homogeneous disease entity in the new classification. Kwon et al [9] stated that a lower rate of ANA positive might result in a higher proportion of other JIA cases. In one multi-ethnic cohort, patients of Asian origin had the lowest rate of early onset ANA-positive arthritis (18%), while those of native North American origin had the highest rate (40%); however, the difference was not significant [10].…”

“…Furthermore, one study that strictly applied the ILAR classification criteria found that up to 30% of the JIA population should be classified as undifferentiated arthritis [8].In a previous issue of this journal, Kwon et al[9] proposed that JIA patients should be reclassified according to RF and ANA to identify homogeneous disease entities, while the number of involved joints and the presence of psoriasis were recommended to be excluded from the ILAR classification. The medical records of 262 JIA patients were investigated retrospectively and the patients were reclassified into six categories using the new classification system proposed by Martini at the 23rd Paediatric Rheumatology European Society Congress (2016) [9]. The new classification system recognizes the following six categories, in which the number of joints criterion was replaced by positivity for RF and ANA or anti-cyclic citrullinated peptide antibody (anti-CCP Ab): systemic JIA, RF-positive JIA, early onset ANA-positive JIA, enthesitis/spondylitis-related JIA, other JIA, and unclassified JIA.…”

“…The new classification system recognizes the following six categories, in which the number of joints criterion was replaced by positivity for RF and ANA or anti-cyclic citrullinated peptide antibody (anti-CCP Ab): systemic JIA, RF-positive JIA, early onset ANA-positive JIA, enthesitis/spondylitis-related JIA, other JIA, and unclassified JIA. Patients not meeting the criteria for the first four categories, or those fitting into more than one category, were classified as other JIA or unclassified JIA [9]. RF-positive JIA, early onset ANA-positive JIA, and enthesitis/spondylitis-related JIA were significantly different in terms of the gender ratio, age of disease onset, and the cumulative number and type of involved joints.…”