COVID-19 in critical care: epidemiology of the first epidemic wave across England, Wales and Northern Ireland.

Purpose: To describe critical care patients with COVID-19 across England, Wales and Northern Ireland and compare them with a historic cohort of patients with other viral pneumonias (non-COVID-19) and with international cohorts of COVID-19.
Methods: Extracted data on patient characteristics, acute illness severity, organ support and outcomes from the Case Mix Programme, the national clinical audit for adult critical care, for a prospective cohort of patients with COVID-19 (February to August 2020) are compared with a recent retrospective cohort of patients with other viral pneumonias (non-COVID-19) (2017-2019) and with other international cohorts of critical care patients with COVID-19, the latter identified from published reports.
Results: 10,834 patients with COVID-19 (70.1% male, median age 60 years, 32.6% non-white ethnicity, 39.4% obese, 8.2% at least one serious comorbidity) were admitted across 289 critical care units. Of these, 36.9% had a PaO ₂ /FiO ₂ ratio of ≤ 13.3 kPa (≤ 100 mmHg) consistent with severe ARDS and 72% received invasive ventilation. Acute hospital mortality was 42%, higher than for 5782 critical care patients with other viral pneumonias (non-COVID-19) (24.7%), and most COVID-19 deaths (88.7%) occurred before 30 days. Meaningful international comparisons were limited due to lack of standardised reporting.
Conclusion: Critical care patients with COVID-19 were disproportionately non-white, from more deprived areas and more likely to be male and obese. Conventional severity scoring appeared not to adequately reflect their acute severity, with the distribution across PaO ₂ /FiO ₂ ratio categories indicating acutely severe respiratory disease. Critical care patients with COVID-19 experience high mortality and place a great burden on critical care services.