Multisystem Inflammatory Syndrome of the Adults (MIS-A) - The undercover threat for young adults. A systematic review and meta-analysis of medical cases.

Background: COVID-19 related syndromes are not yet well described and understood. Multisystem inflammatory syndrome of the adults (MIS-A) is a recently characterized syndrome affecting multiple organs of young adults, causing serious complications, even shock and death.

Objectives: To determine the clinical characteristics, course, and complications of MIS-A in a systematic way and summarize currently used treatments.

Methods: Literature search in March 2023 in PubMed and Scopus databases. Case reports and case-series that fulfilled the CDC criteria for MIS-A were eligible for inclusion.

Results: A total of 71 patients from 60 reports were included. 66% of the patients were male and the mean age of the synthetic cohort was 32.9 years old. The majority (70.4%) of the enrolled cases had no significant medical history. MIS-A was diagnosed after a median of 4 weeks period. All but two patients presented with cardiac symptoms, while the most common secondary diagnostic criterion was abdominal pain, vomiting or diarrhea followed by shock or hypotension. Heart failure therapy and immunomodulation were used as therapeutic options. Although more than half of the cohort was admitted to the Intensive Care Unit (ICU) (n=39) only 4 deaths were reported.

Conclusion: MIS-A can affect patients independently of age, sex, and co-morbidity status, resulting in serious complications, often including severe cardiac disease, shock, acute kidney injury and sometimes death. It can occur immediately after SARS-CoV-2 acute infection until two months later, usually manifesting four weeks after acute disease.