Juvenile idiopathic arthritis: Viva

This is a branching oral built to probe the reasoning that holds the classification, the uveitis and the treat-to-target therapeutics at the centre, and to expose the candidate who has memorised the headline without the safety-critical corners. The questions escalate from the framing to the classification, the uveitis, the methotrexate and the biologics, with deliberate probes into the septic-arthritis mimic and the biologic infection. [2]

Opening question: framing the problem

The examiner opens with the swollen knee for ten weeks and asks: how do you frame this problem in a single sentence, and what is your first step? [2]

A strong answer names the oligoarticular juvenile idiopathic arthritis from the ten-week duration, the morning stiffness and the single joint, and states that the first step is the slit-lamp for the uveitis and the exclusion of the mimics. [2]

Model answer. This child has the oligoarticular juvenile idiopathic arthritis from the arthritis of one joint for more than six weeks in a child under sixteen, with the morning stiffness that improves with activity. The first step is the slit-lamp for the chronic anterior uveitis, because she is young, antinuclear-antibody positive and oligoarticular, which is the highest-risk profile, and the full joint examination and the exclusion of the septic arthritis and the mimics. [1][2]

Probe one: the classification

The examiner presses: describe the ILAR classification, and tell me which subtype is the commonest and what the persistent-versus-extended split means. [1]

A strong answer names the seven categories, the oligoarticular dominance, and the six-month split. The seven ILAR categories are the oligoarticular, the polyarticular rheumatoid-factor negative, the polyarticular rheumatoid-factor positive, the systemic, the psoriatic, the enthesitis-related and the undifferentiated. The oligoarticular is the commonest, at about half to two-thirds. The persistent oligoarticular disease stays in four joints or fewer, and the extended oligoarticular disease develops further joints after the first six months, and the split changes the prognosis and the escalation. [1][2]

Pitfall probe. Why is the rheumatoid factor not used to diagnose the JIA? Because the rheumatoid factor subtypes the disease rather than diagnosing it; it is positive in the rare and aggressive polyarticular rheumatoid-factor-positive category, and it is otherwise negative, and the diagnosis rests on the chronic arthritis with the exclusions. [1]

Probe two: the uveitis and the screening

The examiner asks: what does the slit-lamp show, and what is the screening schedule for this child? [8]

A strong answer names the cells and the flare of the chronic anterior uveitis, the high-risk profile, and the three-monthly slit-lamp. The uveitis is the chronic anterior uveitis, seen on the slit-lamp as the cells and the flare in the anterior chamber, and it is silent in the young child. This child is the high-risk child, because she is young, antinuclear-antibody positive, oligoarticular and within the first four years of the disease, and she is screened every three months. The untreated uveitis scars the eye through the band keratopathy, the posterior synechiae, the cataract and the glaucoma. [8][9]

Pitfall probe. Can the uveitis be detected by the symptoms or the standard eye examination? No, because the chronic anterior uveitis of the JIA is silent, with no pain, no redness and no visual complaint in the young child, and the only detection is the slit-lamp. The screening continues even when the joint disease is inactive, because the uveitis may flare independent of the joint disease. [9]

Probe three: the methotrexate

The examiner asks: what is the methotrexate dose, and what is the monitoring? [4]

A strong answer names the ten to fifteen milligrams per square metre weekly, the subcutaneous route, the folic acid, and the monitoring. The methotrexate is ten to fifteen milligrams per square metre once weekly, given subcutaneously for the better bioavailability, with the folic acid at one milligram daily to reduce the mucosal and the hepatic toxicity. The monitoring includes the full blood count and the liver function, the live vaccines are contraindicated, and the methotrexate takes six to eight weeks to work. [4][2]

Pitfall probe. The child on the methotrexate develops the fever and the neutropenia. What is the diagnosis and the management? The marrow suppression from the methotrexate, and the management is the cessation of the methotrexate, the broad-spectrum antibiotics and the supportive care. The nausea and the intolerance, the other common problem, are managed with the antiemetic and the switch to the subcutaneous route, and they must not be attributed to the non-compliance. [4]

Branch one: the biologic

The examiner pivots: the disease is still active at six months of the methotrexate. What is the next step, and what is the infection risk? [5]

A strong answer names the tumour necrosis factor inhibitor, the etanercept or the adalimumab, and the serious-infection-until-proven-otherwise principle. The etanercept is zero point eight milligrams per kilogram once weekly to a maximum of fifty milligrams, and the adalimumab is twenty-four milligrams per square metre every two weeks to a maximum of forty milligrams, given with the methotrexate. The systematic review of Horneff confirmed the efficacy and the safety of the class. The child on the biologic with the fever has the serious infection until proven otherwise, because the tumour necrosis factor blockade masks the signs, and the empiric broad-spectrum antibiotics come before the cultures return. [5][11]

Branch two: the septic-arthritis mimic

The examiner pivots again: return to the swollen knee, but imagine the child is now febrile, unwell and refusing to bear weight. What is this, and how does your approach change? [2]

A strong answer names the septic arthritis and the Kocher criteria. The septic arthritis is the emergency that must not be missed, and the child with the fever, the inability to bear weight, the raised white-cell count and the raised erythrocyte sedimentation rate is the high-probability septic arthritis by the Kocher criteria. The joint aspirate is the definitive test, and the urgent orthopaedic washout follows. The candidate who can pivot from the chronic JIA to the acute septic arthritis demonstrates the safety the boards reward. [2]

Closing question: the treat-to-target goal

The examiner closes: what is the goal of the treatment, and how is it measured? [6]

A strong answer names the Wallace clinically inactive disease criteria and the treat-to-target principle. The Wallace criteria require no joints with active arthritis, no systemic features, the physician and the parent global scores of zero, and the normal inflammatory markers. The sustained inactive disease for six months on the medication defines the clinical remission on medication, and for twelve months off 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, and the candidate who names the goal and the evidence demonstrates the reasoning the boards reward. [7][6]