Aspirin Management in Incomplete Kawasaki Disease
Children with incomplete Kawasaki disease should receive the identical aspirin regimen as those with complete disease: high-dose aspirin 80–100 mg/kg/day divided into four doses until afebrile for 48–72 hours, then transition to low-dose aspirin 3–5 mg/kg/day once daily for 6–8 weeks if no coronary abnormalities develop. 1, 2
Initial High-Dose Aspirin Protocol
Start high-dose aspirin at 80–100 mg/kg/day divided into four doses immediately upon diagnosis, administered concurrently with IVIG 2 g/kg. 3, 1, 2
Continue this high dose until the patient has been afebrile for 48–72 hours—this is the critical transition point, not a fixed calendar duration. 3, 1, 2
The anti-inflammatory effect of high-dose aspirin is the primary goal during the acute febrile phase. 3
Transition to Low-Dose Aspirin
Once the child has been afebrile for 48–72 hours, immediately reduce to low-dose aspirin 3–5 mg/kg/day as a single daily dose. 3, 1, 2
This low dose provides antiplatelet protection rather than anti-inflammatory effects. 3
Continue low-dose aspirin until 6–8 weeks after disease onset if serial echocardiograms show no coronary abnormalities. 3, 1, 2
Duration Based on Coronary Artery Status
No coronary abnormalities: Discontinue aspirin at 6–8 weeks after disease onset. 1, 2
Any coronary abnormalities detected: Continue low-dose aspirin indefinitely. 3, 2
Small coronary aneurysms: Continue low-dose aspirin 3–5 mg/kg/day indefinitely. 2
Moderate aneurysms (4–6 mm): Add clopidogrel 1 mg/kg/day (maximum 75 mg/day) to low-dose aspirin. 2
Giant aneurysms (≥8 mm): Add warfarin (target INR 2.0–3.0) or therapeutic low-molecular-weight heparin to low-dose aspirin. 1, 2
Monitoring Requirements
Perform echocardiography at diagnosis, 2 weeks, and 6–8 weeks after treatment initiation to guide aspirin duration decisions. 2
Use C-reactive protein (CRP) rather than ESR to monitor inflammation after IVIG, because IVIG artificially elevates ESR values. 2
Frequent echocardiography and ECG during the first 3 months are essential, especially if any coronary abnormalities develop. 1, 2
Critical Safety Considerations
Never co-administer ibuprofen with aspirin in these patients—ibuprofen antagonizes aspirin's irreversible platelet inhibition. 2
Administer annual influenza vaccination to all children on long-term aspirin therapy to reduce Reye syndrome risk during influenza infection. 3, 1, 2
Instruct parents to contact the physician immediately if the child develops symptoms of influenza or varicella while on aspirin. 3, 2
Defer measles, mumps, rubella, and varicella vaccinations for 11 months after high-dose IVIG administration due to interference with vaccine efficacy. 1, 2
Special Considerations for Incomplete Kawasaki Disease
Incomplete Kawasaki disease (fever plus fewer than 4 classic criteria) should be treated identically to complete disease if there is evidence of coronary artery abnormalities or elevated inflammatory markers. 1, 2
Infants under 1 year are at highest risk for incomplete presentations and paradoxically have the highest rates of coronary aneurysms if untreated, making prompt aspirin therapy even more critical. 2
Children presenting after day 10 of illness should still receive the full IVIG plus aspirin regimen if they have ongoing systemic inflammation (CRP > 3.0 mg/dL) with persistent fever or coronary abnormalities. 2
Common Pitfalls to Avoid
Do not reduce aspirin dose based on calendar days alone—the transition depends on fever resolution for 48–72 hours, which may occur at different time points in different patients. 3, 1, 2
Do not discontinue low-dose aspirin prematurely—the full 6–8 week course is necessary even if the child appears clinically well. 3, 1, 2
Do not assume incomplete disease requires less aggressive aspirin therapy—the treatment protocol is identical regardless of whether the presentation is complete or incomplete. 1, 2