Efficacy and safety of intravenous immunoglobulin plus prednisolone therapy in patients with Kawasaki disease (Post RAISE): a multicentre, prospective cohort study.

Background: The RAISE study showed that additional prednisolone improved coronary artery outcomes in patients with Kawasaki disease at high risk of intravenous immunoglobulin (IVIG) resistance. However, no studies have been done to test the steroid regimen used in the RAISE study. We therefore aimed to verify the efficacy and safety of primary IVIG plus prednisolone.

Methods: We did a multicentre, prospective cohort study at 34 hospitals in Japan. We included patients diagnosed with Kawasaki disease according to the Japanese diagnostic criteria, and excluded those who were treated at other hospitals before being transferred to a participating hospital. Patients who were febrile at diagnosis received primary IVIG (2 g/kg per 24 h) and oral aspirin (30 mg/kg per day) until the fever resolved, followed by oral aspirin (5 mg/kg per day) for 2 months after Kawasaki disease onset. We stratified patients using the Kobayashi score into predicted IVIG non-responders (Kobayashi score ≥5) or predicted IVIG responders (Kobayashi score <5). For predicted non-responders, each hospital independently decided whether to add prednisolone (intravenous injection of 2 mg/kg per day for 5 days) to the primary IVIG treatment, according to their respective treatment policy, and we further divided these patients based on the primary treatment received. The primary endpoint was the incidence of coronary artery abnormalities determined by two-dimensional echocardiography at 1 month after the primary treatment in predicted non-responders treated with primary IVIG plus prednisolone. Coronary artery abnormalities were defined according to the criteria of the Japanese Ministry of Health and Welfare and of the American Heart Association (AHA). This study is registered with the University Hospital Medical Information Network Clinical Trials Registry, number UMIN000007133.

Findings: From July 1, 2012, to June 30, 2015, we enrolled 2628 patients with Kawasaki disease, of whom 724 (27·6%) were predicted IVIG non-responders who received IVIG plus prednisolone as primary treatment. 132 (18·2%) of 724 patients did not respond to primary treatment. Among patients with complete data, coronary artery abnormalities were present in 40 (incidence rate 5·9%, 95% CI 4·3-8·0) of 676 patients according to the AHA criteria or in 26 (3·8%, 2·5-5·6) of 677 patients according to the Japanese criteria. Serious adverse events were reported in 12 (1·7%) of 724 patients treated with primary IVIG plus prednisolone; two of these patients had hypertension and bacteraemia that was probably related to prednisolone. One patient died possibly due to severe inflammation from the Kawasaki disease itself.

Interpretation: Primary IVIG plus prednisolone therapy in this study had an effect similar to that seen in the RAISE study in reducing the non-response rate and decreasing the incidence of coronary artery abnormalities. A primary IVIG and prednisolone combination therapy might prevent coronary artery abnormalities and contribute to lowering medical costs.

Funding: Tokyo Metropolitan Government Hospitals and the Japan Kawasaki Disease Research Center.