Background/Purpose: Oligoarticular Juvenile Idiopathic Arthritis (oligoJIA) is the most common JIA subtype. According with the most recent classification criteria¹, monoarticular JIA (monoJIA) is included in the oligoarticular subgroup. We investigated whether patients with persistent monoJIA have different clinical features and outcome as compared to those with oligoarticular disease.

Methods: We evaluated patients with oligoJIA followed at our Pediatric Rheumatology tertiary Center and at least one year of disease duration. MonoJIA we selected on the basis of the exclusive involvement of one single joint during the overall disease course. Each patients was followed with check visits, including ophthalmologic evaluation, every 3-4 months. For each patient, the following parameters were considered: sex, age at onset, presence of joint hypermobility (JH) according to Beighton’s criteria², family history positive for JH, ANA (titer > 1/80 on Hep2 cells), presence and localization of active arthritis, presence of uveitis, treatment during the overall course of the disease and outcome. Treatment was grouped in four categories: intra-articular corticosteroid injection (IACs), non-steroidal anti-inflammatory drugs and/or oral corticosteroids (AIDs), MTX and other disease-modifying anti-rheumatic drugs (DMARDs), and biological agents (BAs). Outcome was defined according to Wallace criteria³ as: clinical remission (CR), clinical remission on medication (CRM) and active disease (A).

Results: 356 patients with oligoJIA, as defined by the ILAR criteria, entered the study. Among these, 23 were excluded for lack of complete data and 12 for follow-up shorter than 1 year. Among the remaining 321, followed for mean 7,6 years (1-21.7), 227 (70.7%) presented oligoJIA and 94 (29.3%) monoJIA. MonoJIA resulted significantly different from oligoJIA for the higher frequency of JH, positive family history for JH, lesser frequency of ANA+ and uveitis and for the less aggressive treatment and better long-term outcome.(Table 1)

Conclusion: MonoJIA seems to be a separate nosological entity from oligoJIA with less incidence of ANA, less uveitis and better long-term outcome. A different treatment approach should be therefore foreseen.

References

1. Petty RE, et al. J Rheumatol 2004;31:390-392
2. Beighton P, et a. Ann Rheum Dis. 1973; 32: 413–418.
3. Wallace CA, et al. J Rheumatol. 2004;31:2290-2294

Table 1