Many patients with coronavirus disease 2019 (COVID–19) need hospital admission for oxygen supplementation. A substantial number of patients need intensive care unit (ICU) admission for escalation of care. ICU doctors and nurses are struggling to provide the best care for patients with COVID–19, but best practice of adjunctive and supportive treatments remains uncertain.

The first objective of this study, named 'PRactice of Adjunctive Treatments in intensive care unit patients with COVID–19' (PRoAcT–COVID), is to describe and compare practice of adjunctive and supportive treatments for COVID–19 in the Netherlands. The second objective is to determine independent associations of adjunctive treatments with outcome.

We conduct a national, multicenter, retrospective observational study, including Intensive care unit (ICU) patients with COVID–19. In this study we will collect data on diverse treatments during the first 28 days in ICU, including (a) types of oxygen support and awake prone positioning; (b) types of ventilatory support, (c) rescue therapies for refractory hypoxemia during invasive ventilation like prone positioning, ventilator adjustments, continuous muscle paralysis, and extracorporeal membrane oxygenation; (d) other adjunctive treatments, like thromboprophylaxis and anticoagulation, antiviral and immunomodulating therapies; and (e) experimental supportive treatments. We also collect typical ICU outcomes, like duration of each adjunctive treatment, duration of ventilation, incidence of tracheostomy, duration of stay in ICU and mortality until day 90.