Background/Purpose: Juvenile idiopathic arthritis (JIA) is a heterogenous disease, classified according to the International League of Associations for Rheumatology (ILAR). Initial treatment is based largely on disease severity; intra-articular injections for oligoarthritis, methotrexate (MTX) for polyarthritis and systemic presentations. The recent licensing of biologic therapies for use in JIA has revolutionised treatment. It is not known what proportion of children who present with polyarthritis will require biologic therapy. Although not studied formally, it is recognised a proportion of children with oligoarthritis, may also require systemic therapy to control symptoms.  Therefore, the aim of this study was to describe prescribing patterns within new onset JIA patients over the first 3 years following presentation to rheumatology.

Methods:

Children with at least 3 years of follow-up within the Childhood Arthritis Prospective Study (CAPS), a prospective observational inception study of inflammatory arthritis, were included.

For analysis, children were grouped into a disease pattern according to the physician-assigned ILAR category and number of active joints at first presentation (baseline): oligoarticular, polyarticular, systemic (sJIA) and enthesitis-related arthritis (ERA). Treatment exposures over the 3 year period were determined and categorised into NSAID, intra-articular steroids, disease modifying anti-rheumatic drug (DMARD) including MTX and biologics including etanercept (ETN) and infliximab (INF).

Results:

790 children had 3 years of follow-up. Of these, 78 had missing ILAR subtype data and were excluded, leaving 712 in total (406 oligoarticular, 221 polyarticular, 42 sJIA and 43 ERA). Over a 3 year period, almost 100% of children with polyarticular and 50% with oligoarticular presentation received a DMARD. 46% with polyarticular and 17% with oligoarticular presentation also received a biologic (Figure 1). The most recent ILAR category among children with oligoarticular onset who received a biologic included 39% extended oligoarthritis, 19% polyarthritis, 4% ERA, 11% other;  27% had persistent oligoarthritis. All sJIA patients were treated with DMARDs with 36% having biologics, primarily ETN and INF. 63% of ERA patients received a DMARD, with 26% later receiving a biologic.

Conclusion:

Over a three year period almost all patients with a polyarticular presentation received treatment with MTX and almost 50% also received a biologic therapy. A high proportion of children with an oligoarticular presentation also went on to receive DMARDs and biologics, with many children receiving this treatment for persistent oligoarthritis. This is despite the lack of clinical trial evidence for effectiveness in this subtype. Further studies on the efficacy/effectiveness in this subtype should be undertaken to ensure appropriate use of advanced therapies in this population.