The postinfectious COVID-19–related multisystem inflammatory syndrome (MIS) first characterized in children has a different presentation in adults that may lead to underrecognition, according to a small, single-center study today in JAMA Network Open.
Conducted by researchers at Vanderbilt University Medical Center, the retrospective study involved 15 patients 21 years and older who met the working definition for MIS in adults (MIS-A) from Mar 1 to Sep 30, 2020, and were hospitalized 14 to 84 days after testing positive for COVID-19 or 15 days before or after SARS-CoV-2 antibody test results identified them as at risk for the syndrome.
Median of four organs affected
The 15 MIS-A patients were compared with 683 hospitalized COVID-19 patients without MIS-A. MIS-A patients were younger than those with acute COVID-19 (median age, 45.1 vs 56.5 years) and more likely to have coronavirus antibodies on serologic testing (9 [60%] vs 0), suggesting a previous infection. Other demographic characteristics and underlying illnesses were similar between the two groups.
Of the MIS-A patients, 9 (60%) had symptoms of COVID-19, and 3 (20%) were hospitalized for coronavirus infection before they were admitted for the related syndrome. Median time between the COVID-19 and MIS-A hospitalizations for these patients was 23 days.
At admission to the hospital for MIS-A, 5 (33.3%) of patients needed intensive care to monitor their blood pressure, 1 (6.7%) required medications to increase blood pressure, and 1 (6.7%) was given noninvasive ventilation. Four patients (26.7%) were given immunosuppressive drugs, and 7 (46.6%) received antibiotics. No participants died.
The median number of organs involved among MIS-A patients was four, most often involving the gastrointestinal, hematologic, and kidney systems. Median age of all 698 patients included in the analysis was 55.8 years, 53.3% were men, 58.2% were White, and 24.2% were Black.
Uncommon, underdiagnosed syndrome
The researchers urged clinicians to be vigilant for signs of MIS-A, the incidence of which was likely underestimated in their study. "Most patients who met the MIS-A criteria were not identified as such by the primary clinical team," they wrote. "These data suggest that, although uncommon, MIS-A has a more heterogeneous clinical presentation than previously appreciated and is commonly underdiagnosed."
The authors said that the MIS-A patients in their study had broader organ involvement and lower disease severity than those reported in a Centers for Disease Control and Prevention study in the United States and the United Kingdom published on Oct 2, 2020, in Morbidity and Mortality Weekly Report.
That study established working criteria for MIS-A, which included severe illness requiring hospital admission in patients 21 and older, a previous or current positive COVID-19 test during hospital admission or in the 12 weeks before, severe dysfunction of at least one non-lung organ system (eg, low blood pressure, shock, cardiac abnormalities, arterial or venous blood clots, thromboembolism, liver damage), test results indicating severe inflammation (eg, elevated C-reactive protein, ferritin, D-dimer, interleukin-6), and the absence of severe respiratory disease.
"Future investigations, including prospective enrollments, are necessary to improve the diagnostic and treatment approaches for patients with MIS-A," the Vanderbilt researchers concluded.
Putting together a clearer picture
In an invited commentary in the same journal, Eric Chow, MD, MPH, of the University of Washington at Seattle, said much remains unknown about MIS, including its underlying mechanisms, incidence, different presentations, and optimal treatment. In children, he said, "therapy frequently includes intravenous immunoglobulins and glucocorticoids, which are extrapolated from the management strategies of Kawasaki disease. Further research will be needed to decide whether these same treatments can be applied to adult cases."
The study, according to Chow, provides another piece of the rare yet clinically important syndrome. "Not only does MIS have important implications for our understanding of SARS-CoV-2 pathology, but it also has the potential to offer new insights in how our immune system functions and its role in hyperinflammation," he said.
Oct 5, 2020, CIDRAP News story "Adults, too, develop rare but severe COVID-related syndrome"