Kawasaki Disease and Kawasaki Disease Shock Syndrome Hospitalization Rates in the United States, 2006-2018

Background: Kawasaki disease (KD) is a febrile illness of unknown etiology. Patients with Kawasaki disease shock syndrome (KDSS) may present with clinical signs of poor perfusion and systolic hypotension in addition to typical KD features. The United States Centers for Disease Control and Prevention analyzes and interprets large hospitalization databases as a mechanism for conducting national KD surveillance. Methods: The Kids' Inpatient Database (KID), the National (Nationwide) Inpatient Sample (NIS), and the IBM MarketScan Commercial (MSC) and MarketScan Medicaid (MSM) databases were analyzed to determine KD-associated hospitalization rates and trends from 2006 to the most recent year of available data. KD and potential KDSS hospitalizations were defined using International Classification of Disease-Clinical Modification codes. Results: For the most recent year, the KD-associated hospitalization rates for children <5 years of age were 19.8 (95% CI: 17.2-22.3, KID: 2016), 19.6 (95% CI: 16.8-22.4, NIS: 2017), 19.3 (MSC: 2018), and 18.4 (MSM: 2018) per 100,000. There was no indication of an increase in KD rates over the time period. Rates of potential KDSS among children <18 years of age, ranging from 0.0 to 0.7 per 100,000, increased; coding indicated potential KDSS for approximately 2.8%-5.3% of KD hospitalizations. Conclusions: Analyses of these large, national databases produced consistent KD-associated hospitalization rates, with no increase over time detected; however, the percentage of KD hospitalizations with potential KDSS increased. Given reports of increasing incidence elsewhere and the recent identification of a novel virus-associated syndrome with possible Kawasaki-like features, continued national surveillance is important to detect changes in disease epidemiology.