Development of a score for early identification of children with Kawasaki disease requiring second-line treatment in multi-ethnic populations in Europe: A multicentre retrospective cohort study.

Background: Early identification of high-risk patients is essential to stratify treatment algorithms of Kawasaki disease (KD) and to appropriately select patients at risk for complicated disease who would benefit from intensified first-line treatment. Several scores have been developed and validated in Asian populations but have shown low sensitivity in predicting intravenous immunoglobulin (IVIG) resistance in non-Asian populations. We sought methods to predict the need for secondary treatment after initial IVIG in non-Asian populations. Methods: We conducted a retrospective, multicenter study including consecutive patients with KD admitted to two tertiary pediatric hospitals in France and Italy from 2005 to 2019. We evaluated the performance of the Kawanet-score and compared it with the performances of initial echocardiography findings, and of a newly proposed score combining the Kawanet-score and initial echocardiography findings. For each score, we assessed the AUC, sensitivity and specificity for predicting the need for second-line treatment. Findings: We included 363 children with KD, 186 from France and 177 from Italy, of whom 57 (16%) required second-line therapy after the first IVIG dose. The Kawanet score, coronary artery dilation or aneurysm with maximal Z-score ≥2.0 at baseline, and abnormal initial echocardiography had a sensitivity of 43%, 55% and 65% and a specificity of 73%, 78%, 73%, respectively, for predicting the need for second-line treatment. The Kawanet-score was significantly improved by combining it with initial echocardiography findings. The best predictive performance (Sensitivity 76%, Specificity 54%) was obtained by combining the Kawanet-score with abnormal initial echocardiography, defined by the presence of either coronary artery maximal Z-score ≥2.0, pericarditis, myocarditis and/or ventricular dysfunction. This score predicted the need for second-line treatment in European, African/Afro-Caribbean and Asian ethnicity with a sensitivity of 80%, 65% and 100%, respectively, and a specificity of 56%, 51% and 61%, respectively. Interpretation: Our study proposes a score that we named the Kawanet-echo score, which allows early identification of children with KD who require a second-line treatment in multi-ethnic populations in Europe. Funding: None.