The Comparative Effectiveness of Intravenous Immunoglobulin and Corticosteroids in Kawasaki Disease: A Nationwide Claim Data Analysis

<b>Background</b>: Kawasaki disease (KD) is an acute type of vasculitis in children, with coronary artery aneurysm (CAA) being its most serious complication. Intravenous immunoglobulin (IVIg) with acetylsalicylic acid (ASA) is the standard treatment, but concerns about IVIg's availability and adverse effects have led to interest in corticosteroids (CSs) as an alternative. This study compares the clinical outcomes of IVIg and CSs in KD patients. <b>Methods</b>: Using South Korean Health Insurance Review and Assessment Service (HIRA) data from 2017 and 2020, we identified children under five diagnosed with KD and treated with IVIg and ASA (the IVIg group) or CSs and ASA (the CS group). Propensity score weighting was applied. The primary outcome was the incidence of CAA, and the secondary outcome included cardiovascular complications. Cox proportional hazards models were used to estimate the hazard ratios (HRs) with 95% confidence intervals (CIs). <b>Results</b>: After adjustment, the CAA incidence was higher in the CS group (6.72%) than in the IVIg group (1.86%) (HR = 3.70; 95% CI: 1.96-6.97; <i>p</i> < 0.0001). Cardiovascular complications were also more frequent in the CS group (HR = 2.87; 95% CI: 1.96-6.97; <i>p</i> < 0.0001). <b>Conclusions</b>: The combination treatment, of CSs and ASA, was associated with a higher risk of CAA and cardiovascular complications compared to that when using IVIg in pediatric KD patients. While CSs may be beneficial as an adjunct therapy in IVIg-resistant cases, they should not replace IVIg as a first-line treatment. Alternative strategies, such as reduced-dose IVIg with adjunctive therapies, should be explored.