Initial Treatment of Kawasaki Disease
The most appropriate initial treatment regimen is A: Aspirin and IVIG. This combination represents the evidence-based standard of care established by the American Heart Association and is the only regimen proven to reduce coronary artery aneurysm risk from 25% to approximately 5% when administered within the first 10 days of illness 1, 2.
Treatment Protocol
Primary Therapy Components
IVIG should be administered at 2 g/kg as a single infusion over 10-12 hours, which has Level A evidence supporting its efficacy in preventing coronary artery abnormalities 1, 2.
High-dose aspirin (80-100 mg/kg/day divided into four doses) should be given concurrently with IVIG and continued until the patient is afebrile for 48-72 hours 1, 2, 3.
After defervescence, aspirin is reduced to low-dose (3-5 mg/kg/day as a single daily dose) and continued for 6-8 weeks if no coronary abnormalities develop 1, 2.
Why Other Options Are Incorrect
Option B (Aspirin and IV corticosteroid) is explicitly contraindicated as initial therapy. The American Heart Association guidelines clearly state that corticosteroids should be withheld unless fever persists after at least two courses of IVIG 1, 4. Early studies suggested steroids may exert detrimental effects when used as initial therapy 1, and current evidence reserves them only for IVIG-resistant cases.
Option C (IVIG and cyclosporine) has no role in initial treatment. Cyclosporine is considered a third-line agent reserved for highly refractory cases that have failed multiple IVIG doses and corticosteroids 3. Using it as initial therapy would be inappropriate and potentially harmful.
Option D (Aspirin and infliximab) is reserved for IVIG-resistant disease. Infliximab, a TNF-α inhibitor, is being studied for patients who fail to respond to initial IVIG treatment but has no established role as first-line therapy 1, 2, 3.
Critical Timing Considerations
Treatment should be initiated within the first 10 days of illness, ideally between days 5-10 1, 2, 3.
Treatment before day 5 may be associated with increased need for IVIG retreatment without additional benefit in preventing cardiac sequelae 1.
Even patients presenting after day 10 should still receive IVIG if they have persistent fever or evidence of ongoing inflammation (elevated ESR or CRP) 1.
Evidence Supporting IVIG Plus Aspirin
Multiple meta-analyses demonstrate a dose-response effect with higher IVIG doses (2 g/kg single infusion) having the greatest efficacy compared to lower or divided doses 1.
The combination reduces coronary artery abnormality risk from 25% untreated to less than 5% with treatment, with only 1% developing giant aneurysms 1, 2.
Approximately 85-90% of patients respond promptly to initial IVIG and aspirin therapy 1, 5.
Common Pitfalls to Avoid
Do not use moderate-dose IVIG (1 g/kg), as research shows it has lower efficacy (27% CAL rate) compared to the standard 2 g/kg regimen 6.
Do not skip or delay IVIG in favor of aspirin alone, as aspirin does not prevent coronary artery abnormalities and serves only as adjunctive anti-inflammatory and antiplatelet therapy 4, 5.
Do not administer corticosteroids as initial therapy, as this violates established protocols and may compromise outcomes 1, 4.
Defer measles and varicella immunizations for 11 months after high-dose IVIG administration 1, 2, 3.
Ensure annual influenza vaccination for children on long-term aspirin therapy due to Reye's syndrome risk 1, 2, 3.
Avoid ibuprofen in children taking aspirin, as it antagonizes aspirin's antiplatelet effects 1, 2, 3.
Management of Non-Responders
Approximately 10-20% of patients develop persistent or recurrent fever ≥36 hours after initial IVIG completion 4, 2, 3, 5.
A second dose of IVIG (2 g/kg) is the recommended next step for IVIG-resistant disease 1, 4, 2.
Only after two IVIG doses fail should corticosteroids (methylprednisolone 20-30 mg/kg IV) or infliximab (5 mg/kg IV) be considered 1, 2, 3.