Nationwide observational study of paediatric inflammatory multisystem syndrome temporally associated with SARS-CoV-2 (PIMS-TS) in the Czech Republic

The worldwide outbreak of the novel 2019 coronavirus disease (COVID-19) has led to recognition of a new immunopathological condition: paediatric inflammatory multisystem syndrome (PIMS-TS). The Czech Republic (CZ) suffered from one of the highest incidences of individuals who tested positive during pandemic waves. The aim of this study was to analyse epidemiological, clinical, and laboratory characteristics of all cases of paediatric inflammatory multisystem syndrome (PIMS-TS) in the Czech Republic (CZ) and their predictors of severe course. We performed a retrospective-prospective nationwide observational study based on patients hospitalised with PIMS-TS in CZ between 1 November 2020 and 31 May 2021. The anonymised data of patients were abstracted from medical record review. Using the inclusion criteria according to World Health Organization definition, 207 patients with PIMS-TS were enrolled in this study. The incidence of PIMS-TS out of all SARS-CoV-2-positive children was 0.9:1,000. The estimated delay between the occurrence of PIMS-TS and the COVID-19 pandemic wave was 3 weeks. The significant initial predictors of myocardial dysfunction included mainly cardiovascular signs (hypotension, oedema, oliguria/anuria, and prolonged capillary refill). During follow-up, most patients (98.8%) had normal cardiac function, with no residual findings. No fatal cases were reported. Conclusions : A 3-week interval in combination with incidence of COVID-19 could help increase pre-test probability of PIMS-TS during pandemic waves in the suspected cases. Although the parameters of the models do not allow one to completely divide patients into high and low risk groups, knowing the most important predictors surely could help clinical management. What is Known: • Preliminary evidence, majority from relatively small, and mostly single-centre patient cohorts, has shown some insights in the basic epidemiological and clinical data of children with a paediatric inflammatory multisystem syndrome temporally associated with SARS-CoV-2 (PIMS-TS) . What is New: • To our knowledge, this is the unique published national population-wide cohort allowing to study the epidemiology (including overall incidence), time gap between viral exposure and clinical symptoms of PIMS-TS, and clinical presentations and outcomes within the individual pandemic waves of COVID-19 that were characterised by various prevailing genetic variants of SARS-CoV-2 . • We estimated 3-week interval as a most probable period between SARS-CoV-2 infection and PIMS-TS based on nationwide population data using cross-correlation method .