Clinical Outcomes of Low-Dose Methotrexate Therapy as a Second-Line Drug for Intravenous Immunoglobulin-Resistant Kawasaki Disease

Purpose: Intravenous immunoglobulin (IVIG) is the standard treatment for Kawasaki disease (KD). However, there is still no standard treatment for IVIG-resistant KD. This study aimed to evaluate the efficacy of low-dose methotrexate (MTX) as a treatment for IVIG-resistant KD. Materials and Methods: We retrospectively analyzed 10-year data for patients with IVIG-resistant KD who were administered MTX at Severance Children's Hospital. Results: The subjects included 75 patients with KD aged 5 months to 9.2 years who had been administered MTX. Their maximum body temperatures decreased significantly within 24 h of therapy. The patients' C-reactive protein levels were significantly lower 1 week after administering the first dose of MTX than those before treatment. No adverse effect for MTX was observed. Conclusion: MTX treatment of IVIG-resistant KD resulted in rapid defervescence, improvement of clinical symptoms, and normalization of acute-phase reactants in all patients. Thus, MTX could be a candidate treatment for IVIG-resistant KD.