135 - ASSOCIATION OF ETHNICITY WITH CLINICAL FEATURES AND CARDIAC OUTCOMES FOR KD VERSUS MULTISYSTEM INFLAMMATORY SYNDROME IN CHILDREN ASSOCIATED WITH COVID-19: A STUDY OF THE INTERNATIONAL KD REGISTRY

Background: KD and multisystem inflammatory syndrome in children (MIS-C) are associated with differing patterns of ethnicity. We sought to determine differential associations of ethnicity with clinical features and cardiac outcomes.

Methods: From January 2020 through October 2023, across 40 sites in the International KD Registry 2146 contemporaneous patients with MIS-C and 1358 with KD were enrolled. Ethnicity was specified for 1466 (68%) of MIS-C and 983 (72%) of KD patients. After excluding patients with more than one ethnicity, we compared the 5 most prevalent ethnicity groups for both KD and MIS-C regarding demographics, presentation, clinical and laboratory features, treatment and cardiac outcomes.

Results: For 1269 included MIS-C patients, ethnicity was White for 439, Hispanic 408, Black 325, Arabic 83 and East Asian for 14. For 769 included KD patients, ethnicity was White for 349, Hispanic 197, Black 120, East Asian 74 and Arabic for 29. Regarding age, MIS-C were significantly older than KD across all ethnicity groups except for East-Asian. MIS-C had higher Z-score BMI than KD across ethnicities except East Asian, with higher Z-score BMI for Hispanic (mean +0.88) and Black (+0.86) than White (+0.45), Arabic (+0.39) and East Asian (+0.38). For MIS-C, White (median 8.67 years), Black (8.50), and Hispanic (8.77) patients were significantly older than East-Asian (4.29) and Arabic (6.42) patients (p < 0.001), with similar ages across KD ethnicity groups (range 2.42 to 3.17). For MIS-C, presentation with shock was more prevalent for Black patients (43%), followed by Hispanic (32%), Arabic (31%), East-Asian (21%) and White (21%)(p < 0.001); more than for KD (range 0% to 5.4%) with no ethnicity differences. Mean LV ejection fraction was significantly lower for MIS-C vs. KD across all ethnicity groups except for East Asian (mean 60.0% vs. 63.3%, p=0.15)(Figure). For MIS-C, Black (mean 54.2%), Hispanic (55.7%), and White (56.7%) had lower LV ejection fraction than Arabic (58.7%) and East Asian (60.0%)(p < 0.001). Less significant differences were noted across KD ethnicity groups (p=0.02). Mean maximum coronary artery Z-score was significantly higher for KD vs. MIS-C for White (mean +1.80 vs. +1.28, p< 001) and Black patients (+2.28 vs. +1.59, p=0.003), but not other ethnic groups. There were no differences across ethnicity groups for KD (p=0.33), but MIS-C had higher Z-scores for Hispanic (+1.77), Black (+1.59) and East-Asian (+1.56) than White (+1.28) and Arabic (+1.24)(p=0.003).

Conclusions: Ethnicity has important associations with demographics, presentation and cardiac outcomes for MIS-C. Findings were less striking for KD.