The inflammatory markers of multisystem inflammatory syndrome in children (MIS‐C) and adolescents associated with COVID‐19: A meta‐analysis

To conduct a systematic review and meta-analysis to characterize inflammatory markers in comparisons of multisystem inflammatory syndrome in children (MIS-C) versus severe/non-severe COVID-19, severe MIS-C versus non-severe MIS-C, and among age groups of MIS-C. Nine databases were searched for studies on inflammatory markers of MIS-C. After quality checks, data were pooled using a fixed or random effects model. Inflammatory markers included white blood cell count (WBC) or leukocytes, absolute lymphocyte count (ALC), absolute neutrophil count (ANC), platelet count (PLT), C-reactive protein (CRP), procalcitonin (PCT), ferritin, D-dimer, lactate dehydrogenase (LDH), fibrinogen, and erythrocyte sedimentation rate (ESR) for comparisons by severity and age. Twenty-one studies with 1735 participants yielded 787 MIS-C patients. Compared to non-severe COVID-19 patients, MIS-C patients had lower ALC and higher ANC, CRP, and D-dimer levels. Compared to severe COVID-19 patients, MIS-C patients had lower LDH and PLT counts and higher ESR levels. Severe MIS-C patients had higher levels of WBC, ANC, CRP, D-dimer, and ferritin than non-severe MIS-C patients. For MIS-C, younger children (0-5 years) had lower CRP and ferritin levels than middle-aged/older children/adolescents. Measurement of inflammatory markers might assist clinicians in accurate evaluation and diagnosis of MIS-C and the associated disorders.