Juvenile idiopathic arthritis: SAQ

This child has the classic presentation of the oligoarticular juvenile idiopathic arthritis with the chronic anterior uveitis, and the task is to outline the ILAR classification, the persistent-versus-extended split, the uveitis screening schedule, and the stepwise treat-to-target management with the Wallace criteria as the goal. ^[1][2]

Question 1 (10 marks)

Outline the ILAR classification of juvenile idiopathic arthritis, the persistent-versus-extended split, and the uveitis screening schedule for this child. ^[1]

A full-mark answer covers the seven categories, the oligoarticular dominance, the six-month split, and the three-monthly slit-lamp for the high-risk child. ^[2]

ILAR definition and the seven categories (3 marks). The ILAR classification requires the arthritis of one or more joints for at least six weeks in a child under sixteen with other causes excluded. The seven categories are the oligoarticular, the commonest at about half to two-thirds; the polyarticular rheumatoid-factor negative; the polyarticular rheumatoid-factor positive; the systemic; the psoriatic; the enthesitis-related; and the undifferentiated. The oligoarticular is defined as one to four joints in the first six months, and it is the subtype with the highest uveitis risk. ^[1]

The persistent-versus-extended split (3 marks). The oligoarticular disease splits at the six-month mark into the persistent, where the disease stays in four joints or fewer, and the extended, where further joints become involved after the first six months. The persistent carries the better prognosis and may need only the intra-articular injection, while the extended carries the worse prognosis and warrants the methotrexate and the closer surveillance. This child has one joint at presentation, so she is oligoarticular, and the split will be determined at the six-month mark. ^[1][2]

The uveitis risk profile and the screening schedule (4 marks). The chronic anterior uveitis affects roughly ten to twenty percent of the oligoarticular and the polyarticular rheumatoid-factor-negative children, and it is silent. The high-risk child is the one who is young, antinuclear-antibody positive, oligoarticular and within the first four years of the disease, and this child meets all four criteria. The high-risk child is screened by the slit-lamp every three months for the first four years, because the window of the highest uveitis incidence is the first four years. The moderate-risk child is screened every six to twelve months. The uveitis is detected on the slit-lamp as the cells and the flare, and the untreated uveitis scars the eye through the band keratopathy, the posterior synechiae, the cataract and the glaucoma. ^[8][9]