Background In the recent years the classification of Juvenile Idiopathic Arthritis (JIA) according to the International League of Associations for Rheumatology has been questioned. One of the questions posed is if patients with a positive Antinuclear Antibody (ANA) should be a separate category. ANA positivity is found in all subtypes but is more frequent in patients with oligoarthritis, rheumatoid factor negative polyarthritis, psoriatic arthritis and undifferentiated arthritis. Previous studies have shown contradicting evidence to support the separation of patients based on ANA status.
Objectives The aim of this study is to evaluate the clinical and disease activity features of ANA positive patients in comparison to the ANA negative patients at disease onset and last follow-up.
Methods All patients diagnosed with JIA since January 2000 until May 2014 were included. ANA positivity was defined as at least 2 positive results with a titer of equal or higher than 1:160 (indirect immunofluorescence assays on HEp-2 cells). Demographic and clinical features were collected. Remission at last follow-up was defined by Wallace criteria for remission on (>6 months) and off (>12 months) medication.
Results A total of 648 patients were diagnosed with JIA during the inclusion period. 236 (36%) were ANA positive and 412 (64%) ANA negative. The ANA positive patients show a more profound female predominance than ANA negative patients (respectively 77% compared to 56%). The mean age at diagnosis of ANA positive patients was 6.5 years and disease duration at last follow-up 6.3 years, compared to 9.3 years and 4.8 years in the ANA negative group. Subtypes representation in the ANA positive group were; 2% systemic, 41% oligoarthritis persistent, 21% oligoarthritis extended, 25% polyarthritis RF negative, 3% polyarthritis RF positive, 4% psoriatic arthritis, 3% ERA, 1% undifferentiated. Subtypes representation in the ANA negative group were; 11% systemic, 31% oligoarthritis persistent, 12% oligoarthritis extended, 19% polyarthritis RF negative, 3% polyarthritis RF positive, 9% psoriatic arthritis, 8% ERA, 7% undifferentiated. The joint count at diagnosis is equal in both the ANA positive and ANA negative group (mean 3 joints). Uveitis was present in 18% of the ANA positive patients and 2.4% in ANA negative patients. Disease outcome is comparable in both the ANA positive and ANA negative group; remission on medication more than 6 months 26% for both groups, remission off medication for more than 12 months 50% ANA positive group and 53% ANA negative group, no remission was achieved at last follow-up in 8% of ANA positive patients compared to 5% of ANA negative patients. The remaining patients had achieved remission at last follow-up on medication less than 6 months in 7% in both groups and remission off medication for less than 12 months in 9% in both groups.
Conclusions Our findings show that ANA positive patients show certain characteristics such as associated uveitis and predominance of oligoarthritis and corresponding female predominance. Disease activity at diagnosis measured as active joint count was not different. More than 75% of all JIA patients had reached remission on or off medication at last follow-up and this was irrespective of the ANA status. This initial analysis does not support the hypothesis to separate JIA patients based on ANA status.
Disclosure of Interest None declared