Background Oligoarticular Juvenile Idiopathic Arthritis (oJIA) is the most frequent JIA subtype. It is characterized by early onset, high risk of chronic uveitis and high prevalence ANA positivity. During the last few years, new treatments have been introduced for this subtype but little is known about the long-term outcome.

Objectives To report the long-term outcome of oJIA followed at a single pediatric rheumatology center.

Methods We conducted a retrospective study in a cohort of children affected by oJIA, defined by the ILAR criteria¹. Patients with at least two years follow-up and complete clinical data available, were evaluated. Clinical and laboratory data at disease onset and at the last follow-up were collected. They included sex, age, activity of arthritis or uveitis, ANA, treatment and outcome according with the Wallace criteria². In particular, clinical remission (CR) was defined when the disease was inactive for at least 12 months while off all medications, clinical remission on medication (CRM) in presence of inactive disease for at least 6 months while on medication, active disease (A) when active arthritis and/or uveitis were present.

Results 274 oJIA patients (224 F, 50 M), aged 11.5 (4.5) years and followed for 6.6 (3.8) years entered the study. At disease onset 83.9% were ANA-positive, 20.8% had uveitis and arthritis involved the lower limbs in 92.7%. The first treatment approach was intra-articular corticosteroids (IACS) injection in 72.3%, oral nonsteroidal anti-inflammatory drugs (NSAIDs) and/or corticosteroids (CS) in 21.2%, methotrexate (MTX) in 6.6%. At the last follow up visit, the prevalence of ANA-positivity significantly decreased to 77.0%, uveitis occurred in 27.4% of the patients and active arthritis was present in only 11.3%. As for treatment, 47.8% of the patients were off treatment, 25.5% were on MTX and 16.8% on anti-TNF agents (11.7% for uveitis, 5.1% for arthritis). Clinical remission was observed in 47.4%, CRM in 40.1% and arthritis was still active in 12.5%. Of 163 patients with at least 5 years follow up, 47.9% were in CR, 25.2% were in CRM for arthritis and 16.6% in CRM for uveitis, 10.4% still had active disease. The persistent oJIA subtype was present in 78.8% of the subjects, extended oJIA in 21.2%. No significant differences were observed for prevalence of age at disease onset, gender, ANA-positivity and uveitis between the two subtypes. Conversely, the long-term disease outcome at 5-year follow-up was significantly worse for the extended subtype (CR 20.9 vs 57.5%, CRM 58.2 vs 35.8%, A 20.9 vs 6.7%, p<0.0001).

Conclusions In general, oligoarticular JIA has a good long-term outcome, with almost half of the patients in clinical remission at 5 years follow up. Uveitis is an important cause of disability and represents the main indication for the use of biological agents. The extended oJIA subtype has more severe disease course, needs more aggressive treatment approach and has a worse long-term outcome than the persistent one.

References

1. Petty RE, et al. J Rheumatol 2004;31:390-392

2. Wallace CA, et al. J Rheumatol. 2004;31:2290-2294

Acknowledgements We acknowledge IL VOLO, no-profit Association for Rheumatic Diseases in Children, ONLUS, Padua, Italy, for having supported the study with a dedicated grant.

Disclosure of Interest None declared