2.2 Study selection
No time or language restriction was applied. Inclusion criteria were as follows: (1) Types of Studies: retrospective, prospective, observational, descriptive or case-control studies reporting COVID-19 patients (<18 years) with the multisystem inflammatory syndrome; (2) Subjects: diagnosed patients with COVID-19 (3) Exposure intervention: COVID-19 patients diagnosed with Real-Time polymerase chain reaction, radiological imaging, or both with at least 4 out of 5 principal features of typical Kawasaki syndrome (apart of the persistent fever at least for five days): (i) bilateral conjunctival injection, (ii) oral changes such as cracked and erythematous lips and strawberry tongue, (iii) cervical lymphadenopathy, (iv) extremity changes such as erythema or palm and sole desquamation, and (v) polymorphous rash. Patients presented with fever lasting five or more days and with 2-3 of these findings were considered as incomplete (atypical) Kawasaki disease18; and (4) Outcome indicator: the mean and standard deviation or median and interquartile range for COVID-19 related complications and mortality.
The following exclusion criteria were considered: (1) Case reports, reviews, editorial materials, conference abstracts, summaries of discussions, (2) Insufficient reported data information; or (3) In vitro or in vivo studies.