Editor’s Note: Ha Le (she/hers) is a resident physician in pediatrics at UCSF, whose passions include medical education, social justice, and narrative medicine. - Rachel Y. Moon, MD, Associate Editor, Digital Media, Pediatrics
The COVID-19 pandemic has had far-reaching implications, from changing work and school environments to exacerbating health disparities. One consequence within the pediatric community has been the advent of multisystem inflammatory syndrome (MIS-C), a severe condition with fever, signs of inflammation, and multi-organ disease, seen recently in children infected with SARS-CoV-2. Diagnosis of MIS-C is complicated by its clinical similarity to Kawasaki disease (KD).
As another surge ensues and the CDC announces an updated vaccine, COVID-19 – along with its resulting complications – remains a critical issue in 2023. Large-scale studies comparing MIS-C and KD are sparse, however, Dr. Matthew J. Molloy at the University of Cincinnati and colleagues at 6 universities and the Children’s Hospital Association sought to address this issue by better characterizing the severity of MIS-C compared to that of KD in an article being early released in Pediatrics this week (10.1542/peds.2023-062101).
The cross-sectional study utilized data for children aged ³30 days to <21 years hospitalized for MIS-C and/or KD in 39 pediatric hospitals across 34 US states. From April 2020 to end of May 2022, termed the COVID-19 period, the researchers compared the number of shock cases in hospitalized children with MIS-C and those with KD, along with the number of deaths. Illness severity was characterized by the Hospitalization Resource Intensity Scores for Kids (H-RISK) and extracorporeal membrane oxygenation (ECMO) usage.
The authors found that during the COVID-19 period
- 4,868 children were hospitalized for MIS-C and 2,387 patients for KD.
- Compared to patients with KD, those with MIS-C were increasingly older, Black patients, on government insurance, or medically complex.
- 7% of the patients with MIS-C met criteria for shock compared to 5.1% of patients with KD, with older patients experiencing higher rates of shock.
- 69% of the patients with MIS-C required extracorporeal membrane oxygenation (ECMO) during hospitalization, compared to 2% of patients with KD, and there were 53 deaths among the MIS-C cohort compared to zero deaths among those with KD.
These data corroborate the higher burden of illness with MIS-C seen in prior case series and observational studies.
Molloy and colleagues further assessed temporal trends. They found a gradual decline of MIS-C hospitalizations over the COVID-19 period, with a 2% decreased odds of shock every 2 weeks among patients with MIS-C. No such decrease was seen among patients with KD.
While the study findings help to better differentiate the illness course of MIS-C from KD, they also present new topics worthy of investigation.
Regarding the higher mortality among those with MIS-C, the authors note, “further investigation is needed to determine the specific causes of MIS-C mortality and modifiable risk factors that may contribute.” The exact factor for the declining morbidity of MIS-C as the COVID-19 pandemic progressed also remains unclear. A better understanding is critical for lessening the effects of MIS-C in future patients.
Lastly, the racial and ethnic disparities shown within the data suggest that further research into health equity and COVID-19, particularly regarding MIS-C, is necessary.
I would encourage everyone who cares for children – and particularly clinicians interested in MIS-C – to read the article and learn more.
