The Natural History of Severe Acute Respiratory Syndrome Coronavirus 2-Related Multisystem Inflammatory Syndrome in Children: A Systematic Review

Background. The clinical manifestations and natural history of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-related multisystem inflammatory syndrome in children (MIS-C) are poorly defined. Using a systematic review of individual cases and case series and collating elements of the clinical course, the objective of this study was to provide a detailed clinical description and natural history of MIS-C. Methods. Case reports and series of MIS-C were recovered from repeated MEDLINE searches, a single EMBASE search, and table of contents reviews of major general medicine and pediatric journals performed between June 3 and July 23, 2020. Fever, evidence of inflammation, and evidence of organ dysfunction were required for inclusion. Results. MEDLINE and EMBASE searches produced 129 articles, and 10 articles were identified from journal contents or article bibliographies; 16 reports describing 505 children with MIS-C comprise this review. Thirty-two children (14.7%) had negative results for SARS-CoV-2 by nucleic acid and/or antibody testing. The weighted median age was 9 years (6 months to 20 years). Clinical findings included fever (100%), gastrointestinal symptoms (88.0%), rash (59.2%), conjunctivitis (50.0%), cheilitis/"strawberry tongue" (55.7%), or extremity edema/erythema (47.5%). Median serum C-reactive protein, ferritin, fibrinogen, and D-dimer concentrations were above the normal range. Intravenous gammaglobulin (78.1%) and methylprednisolone/prednisone (57.6%) were the most common therapeutic interventions; immunomodulation was used in 24.3% of cases. Myocardial dysfunction requiring ionotropic support (57.4%) plus extracorporeal membrane oxygenation (5.3%), respiratory distress requiring mechanical ventilation (26.1%), and acute kidney injury (11.9%) were the major complications; anticoagulation was used commonly (54.4%), but thrombotic events occurred rarely (3.5%). Seven (1.4%) children died. Conclusions. MIS-C following SARS-CoV-2 infection frequently presents with gastrointestinal complaints and/or rash; conjunctivitis, cheilitis, and/or extremity changes also occur frequently. Serious complications occur frequently and respond to aggressive supportive therapy.