The Risk stratification in COVID-19 patients in the ICU (RISC-19-ICU) registry was founded during the emerging SARS-CoV-2 pandemic. COVID-19 is a novel disease caused by infection with the SARS-CoV-2 virus that was first described in December 2019. The disease has spread exponentially in many countries and has reached global pandemic status within three months. According to first experience, hospitalization was required in approximately 20 % of cases and severe, life-threatening illness resulted in approximately 10 %. In some countries, health care systems were overwhelmed by the rapid increase in critically ill patients that far exceeded their capacity. It is thus of utmost importance to gain knowledge about the characteristics and course of critically ill patients with COVID-19 and to stratify these patients according to their risk for further deterioration. A key part of fighting this pandemic is to exchange scientific information and advance our understanding of the disease.

The Risk stratification in COVID-19 patients in the ICU (RISC-19-ICU) registry aims to collect an anonymized dataset to characterize patients that develop life-threatening critical illness due to COVID-19 and make it accessible to collaborative analysis.

The data collected may be composed of a core dataset and/or an extended dataset. The core dataset consists of a basic set of parameters, of which many are commonly generated during treatment of critically ill patients with COVID-19 in an intensive care unit (the individual parameters are marked yellow in the attached case report forms, and are clearly marked on the electronic case report forms during data entry). The extended dataset consists of parameters that may be measured during treatment of critically ill patients with COVID-19 in an intensive care unit, depending on clinical practice, indication and availability of the measurement method. The data accumulating in the registry as the pandemic or subsequent waves develop are made available to the collaborators to support an optimal response to the pandemic threat. The information gained on the initial characteristics and disease course via the RISC-19-ICU registry may contribute to a better understanding of the risk factors for developing critical illness due to COVID-19 and for an unfavorable disease course, and thus support informed patient triage and management decisions.

Initial research questions are (I) to perform risk stratification of critically ill patients with COVID-19 to find predictors associated with the development of critical illness due to COVID-19: characterization of the study population, which are critically ill patients with COVID-19: inflammation, oxygenation, circulatory function, among other parameters collected in the registry, and (II) to perform risk stratification of critically ill patients with COVID-19 to predict outcome after ICU admission (ICU mortality, ICU length of stay): characterization of patients grouped by disease course in the ICU, based on inflammation, oxygenation, circulatory function, and other parameters collected in the registry.

Inclusion Criteria:

• Admission to an intensive care unit in a collaborating center due to COVID-19

Exclusion Criteria:

• Missing ethical approval

Patients admitted to an intensive care unit in a collaborating center due to COVID-19

• Each collaborator's data is available for their own use
• The collaborators are encouraged to share their analysis code (the standard is R code)
• Analysis on the entire registry dataset may be performed using the same analysis pathway. To request analysis on the entire dataset, a protocol may be submitted to the board
• The board may make some descriptive data publicly available to support the coordination of the response to the pandemic threat
• Scientific findings will be jointly published in a scientific journal according to a collaboration agreement