Researchers are reporting new insights into a mysterious post-COVID illness called multisystem inflammatory syndrome in adults, or MIS-A. They found that the condition has more varying clinical signs than previously known and is often underdiagnosed. The syndrome is similar to a rare but serious condition that was previously identified in children called MIS-C.
In a retrospective single-center study, the researchers identified 839 patients who were hospitalized with a positive test result for SARS-CoV-2, the virus that causes COVID-19, during the study’s time frame (March 1 through September 30, 2020). Of these, they identified 15 patients who met the diagnostic criteria for MIS-A.
The researchers found that those with an MIS-A diagnosis tended to be younger than those admitted for acute COVID symptoms (median age 45 vs 56 years) and were more likely to have evidence of SARS-CoV-2 indicated by blood testing. About 60% of the patients with MIS-A had acute COVID-19 symptoms and 20% required admission for acute COVID before being admitted for MIS-A. In general, the patients with MIS-A had a broader distribution of organ involvement and lower illness severity compared to previous studies. The gastrointestinal, blood, and kidney systems were mostly affected in these patients. Treatments included immunosuppressive therapy and antibiotic therapy and no patients died during the study period.
Further studies are needed to improve the diagnosis and treatment of this condition, which is likely underdiagnosed, the researchers said. Their study, partly funded by the NHLBI, appeared in JAMA Network Open.