Odds of patients with MIS-C experiencing shock have fallen
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Key takeaways:
- Children with MIS-C were seven times more likely to experienced shock than those with Kawasaki disease.
- However, the odds of shock over time have significantly decreased among patients with MIS-C.
Hospitalized patients with multisystem inflammatory syndrome in children — or MIS-C —are far more likely to experience shock than those hospitalized with Kawasaki disease, according to a study.
However, researchers also found that the proportion of children with MIS-C — a potentially serious complication of SARS-CoV-2 infection — who also experience shock has decreased over time.
“Research examining the change in illness severity for MIS-C over time was lacking,” Matthew J. Molloy, MD, MPH, attending physician in the division of hospital medicine at Cincinnati Children’s Hospital Medical Center, told Healio.
“We also noted an apparent change in the epidemiology of Kawasaki disease (KD), an inflammatory condition with similarities to MIS-C, yet data on the volume of hospitalizations for KD were also lacking,” Molloy said. “We gathered our team to research these unanswered questions.”
Molloy and colleagues searched the Pediatric Health Information System administrative database for hospitalizations for MIS-C and KD during the COVID-19 pandemic, from April 2020 to May 2022. They studied the number of hospitalizations and proportion of hospitalizations with shock over time, with the primary outcome being the presence of shock during the hospitalization.
“Our team previously developed an algorithm to identify hospitalizations for MIS-C in administrative databases prior to the implementation of the ICD-10 code for MIS-C in January 2021,” Molloy said.
The researchers compared the proportion of hospitalizations with shock during each COVID-19 wave and for each age category, and evaluated the proportion of hospitalizations with shock over time using models that adjusted for age and hospital clustering.
The study included 4,868 hospitalizations for MIS-C — “the largest MIS-C study to date,” Molloy said — and 2,387 hospitalizations for KD.
Overall, patients with MIS-C were usually older than patients with KD, with 79.1% of the former group being aged 5 years or older, compared with to 22.3% in the latter group. Patients with MIS-C were also much more likely to meet the researchers’ definition of shock, 38.7% to 5.1%.
There were 43 deaths, all in the MIS-C group.
“We also found that the volume of hospitalizations for MIS-C rose and fell with COVID-19 waves, as reported by other groups,” Molloy said. “Our most important finding was that the odds of shock in patients hospitalized with MIS-C showed a significant decrease over time with an adjusted odds ratio of 0.98, representing a 2% decreased odds of shock every 2 weeks over the course of the COVID-19 pandemic.”
Potential explanations for this decrease in illness severity, Molloy said, include improved identification of patients with MIS-C, improved treatment, the impact of vaccination and infection-induced immunity, and potential differences with different SARS-CoV-2 variants.
Molloy and colleagues also found that there was a higher proportion of non-Hispanic Black children in the MIS-C group that was not explained by differences in neighborhood-level resources.
“This finding adds to the racial and ethnic inequities in the incidence, severity of illness, and outcomes in children with MIS-C that have been noted by others,” Molloy said. “It is critically important to understand what is driving these inequities.”
Although the likelihood of severe illness from MIS-C has decreased over time, Molloy said, “MIS-C remains a serious condition to consider,” with children aged 12 years or older more likely to experience shock.
Prior research has shown that vaccination reduces the risk for MIS-C to around one in a million. Molloy is interested in the “impact of vaccination-induced or infection-induced COVID-19 immunity on the risk of developing shock or death in patients with MIS-C.”
“This may provide further evidence of the benefits of COVID-19 vaccination,” Molloy said. “Ongoing research into risk factors like age as the epidemiology of MIS-C continues to evolve will help pediatricians identify those at highest risk of severe disease.”
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