Multisystem Inflammatory Syndrome in Adults (MIS-A) – Case Definition

Case Definition for MIS-A

A patient aged ≥21 years hospitalized for ≥24 hours, or with an illness resulting in death, who meets the following clinical and laboratory criteria. The patient should not have a more likely alternative diagnosis for the illness (e.g., bacterial sepsis, exacerbation of a chronic medical condition).
  1. Clinical Criteria Subjective fever or documented fever (≥38.0 C) for ≥24 hours prior to hospitalization or within the first THREE days of hospitalization* and at least THREE of the following clinical criteria occurring prior to hospitalization or within the first THREE days of hospitalization*. At least ONE must be a primary clinical criterion.
     
    1. Primary clinical criteria
      1. Severe cardiac illnessIncludes myocarditis, pericarditis, coronary artery dilatation/aneurysm, or new-onset right or left ventricular dysfunction (LVEF<50%), 2nd/3rd degree A-V block, or ventricular tachycardia. (Note: cardiac arrest alone does not meet this criterion)
      2. Rash AND non-purulent conjunctivitis
    2. Secondary clinical criteria
      1. New-onset neurologic signs and symptoms Includes encephalopathy in a patient without prior cognitive impairment, seizures, meningeal signs, or peripheral neuropathy (including Guillain-Barré syndrome) 
      2. Shock or hypotension not attributable to medical therapy (e.g., sedation, renal replacement therapy)
      3. Abdominal pain, vomiting, or diarrhea
      4. Thrombocytopenia (platelet count <150,000/ microliter)
  2. Laboratory evidence The presence of laboratory evidence of inflammation AND SARS-CoV-2 infection.
     
    1. Elevated levels of at least TWO of the following: C-reactive protein, ferritin, IL-6, erythrocyte sedimentation rate, procalcitonin
    2. A positive SARS-CoV-2 test during the current illness by RT-PCR, serology, or antigen detection

NOTE: *These criteria must be met by the end of hospital day 3, where the date of hospital admission is hospital day 0.

Coding

New ICD-10-CM Diagnosis Code for MIS: M35.81external icon

  • Applicable to:
    • MIS-A
    • MIS-C
    • Multisystem inflammatory syndrome in adults
    • Multisystem inflammatory syndrome in children
    • Pediatric inflammatory multisystem syndrome
    • PIMS
  • Use additional code, if applicable, for:
  • Code first, if applicable, COVID-19 (U07.1external icon)
  • Code also any associated complications
Page last reviewed: May 11, 2021