98 - KAWASAKI DISEASE OCCURRENCE IN THE UNITED STATES, 2006-2020

Background/Aims. In the United States, most children with Kawasaki disease (KD) are hospitalized; hospitalization data may therefore be used to estimate disease incidence. The US Centers for Disease Control and Prevention (CDC) conducts national surveillance for KD through analyses of large hospitalization datasets. Data through 2020 are of particular interest due to the emergence of COVID-19 and the potential impacts of social distancing measures.

Methods. The Kids’ Inpatient Database (KID, 2012, 2016, 2019) and the Nationwide Inpatient Sample (NIS, 2006-2020) were analyzed to determine KD-associated hospitalization rates and trends. KD hospitalizations were identified using International Classification of Disease-Clinical Modification (ICD-CM) codes. The KD rate for 2020 was compared to the rate in previous years; the emergence of multisystem inflammatory syndrome in children (MIS-C), which shares certain characteristics with KD, was adjusted for by excluding identified KD cases with a MIS-C ICD-CM code and/or a classification of potential KD shock syndrome (KDSS), which could also indicate MIS-C. Potential KDSS cases were defined as those with a KD diagnostic code in conjunction with a code indicative of at least one of three other diagnoses: hypotension, shock, and sepsis. Trends in other diseases (e.g., urinary tract infection (UTI), pyelonephritis) during the same period were also assessed.

Results. The KD-associated hospitalization rate for children < 5 years of age using the KID was 18.9 (95% CI: 16.6-21.1) per 100,000 children in 2019, 19.7 (95% CI: 17.2-22.3) in 2016, and 18.1 (95% CI: 16.0-20.2) in 2012. The average annual KD-associated hospitalization rate per 100,000 children < 5 years of age from 2006-2020 using the NIS was 17.9 (95% CI: 17.0-18.8). The highest rate was in 2010 (21.6; 95% CI: 15.9-27.3) and, for the most recent 9 years, the lowest rate was in 2020 (15.0; 95% CI: 12.6-17.4). The rate of patients < 5 years coded with KD, excluding MIS-C and KDSS-associated codes, was significantly lower in 2020 compared to 2018 and 2019 (RR 0.7, 95% CI: 0.6-0.9). Similarly, the UTI rate in 2020 was significantly lower, while the 2020 pyelonephritis rate was not.

Discussion/Conclusions. Analyses of KID and NIS hospitalization data, 2006-2020, showed relatively stable annual KD incidence rates, although there was a decrease in KD cases diagnosed in 2020, the first year of the COVID-19 pandemic. Comparisons with trends in other diseases during the same period may offer insight into the etiology of KD.