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]

Question 2 (10 marks)

Discuss the stepwise treat-to-target management of this child, from the non-steroidal anti-inflammatory drugs through the methotrexate to the biologics, with the Wallace criteria as the goal, and the management of the uveitis. [2]

A full-mark answer covers the stepwise pharmacotherapy, the methotrexate dose and monitoring, the biologic dose, the Wallace criteria, and the uveitis treatment. [6]

The stepwise pharmacotherapy (4 marks). The first step is the non-steroidal anti-inflammatory drugs and the intra-articular corticosteroid injection of the active joint, with the triamcinolone hexacetonide for the longer duration. For the oligoarticular child with a single joint, the intra-articular injection may be the only treatment needed. The second step, if the disease is active at three months or if the uveitis is present, is the methotrexate at ten to fifteen milligrams per square metre once weekly, subcutaneously for the better bioavailability, with the folic acid to reduce the mucosal and the hepatic toxicity. The methotrexate takes six to eight weeks to work. The third step, if the disease is active at three to six months of the methotrexate, is the tumour necrosis factor inhibitor, the etanercept or the adalimumab. [4][2]

The methotrexate and the biologic doses (3 marks). The methotrexate is ten to fifteen milligrams per square metre once weekly, given subcutaneously, with the folic acid at one milligram daily. The monitoring includes the full blood count and the liver function, the live vaccines are contraindicated, and the nausea and the intolerance are managed with the antiemetic and the switch to the subcutaneous route. The etanercept is zero point eight milligrams per kilogram once weekly to a maximum of fifty milligrams, established in the landmark trial of Lovell and the Pediatric Rheumatology Collaborative Study Group. The adalimumab is twenty-four milligrams per square metre every two weeks to a maximum of forty milligrams, given with the methotrexate, and it has the added benefit for the uveitis. [4][5]

The Wallace criteria and the treat-to-target goal (2 marks). The Wallace clinically inactive disease criteria require no joints with active arthritis, no systemic features, the physician global score of zero, the parent global score of zero, and the normal inflammatory markers. The sustained inactive disease for at least six months on the medication defines the clinical remission on medication, and the sustained inactive disease for at least twelve months off all the medication defines the clinical remission off medication. The TREAT trial of Wallace and the colleagues tested the early aggressive therapy and shaped the treat-to-target care. [7][6]

The uveitis management (1 mark). The uveitis management, guided by the SHARE initiative consensus of Constantin, begins with the topical corticosteroid and the mydriatic, and escalates to the methotrexate for the steroid-sparing and the anti-tumour-necrosis-factor, particularly the adalimumab, for the resistant disease. [8]