Clinical characteristics and determinants of mortality in coronavirus disease 2019 (COVID-19) patients on an intensive care unit—a retrospective explorative 1-year all-comers study

BACKGROUND: Clinical outcome in patients with coronavirus disease 2019 (COVID-19) requiring treatment on intensive care units (ICU) remains unfavourable. The aim of this retrospective study was to exploratively identify potential predictors of unfavourable outcome in ICU patients diagnosed with COVID-19. METHODS: In all patients with COVID-19 (n=50) or severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) as comorbidity (n=11) at our ICU we assessed clinical, respiratory and laboratory parameters with a potential role for outcome. Main outcome variables were intubation and mortality rates. RESULTS: Between March 2020 and March 2021, 573 patients were hospitalized with SARS-CoV-2 infection. Of these, 61 patients (10.6%, 44.3% women) aged 66.4±13.3 were admitted to ICU. A proportion of 73.8% of patients had moderate or severe acute respiratory distress syndrome (ARDS). COVID-19 patients differed clinically from those with SARS-CoV-2 as comorbidity, such as severe heart or renal failure or sepsis as the leading cause of ICU admission, despite similar mortality rates (44.0% vs. 45.5%, P>0.5). Among COVID-19 patients, those who died had more often severe ARDS (91% vs. 46%, P=0.001), longer non-invasive ventilation (NIV) therapy prior to ICU (6.3±5.9 vs. 2.5±2.0 days, P=0.046), and higher interleukin-6 (IL-6) and lactate dehydrogenase (LDH) values as compared to survivors. In multivariable analysis, NIV duration ≥5 days on admission [odds ratio (OR): 42.20, 95% confidence interval (CI): 1.22 to >99, P=0.038] and IL-6 [OR: 4.08, 95% CI: 1.16–14.33, P=0.028] remained independently predictive of mortality. In worsening tertiles of partial pressure of oxygen (pO(2))/inspiratory oxygen fraction (FiO(2)) on admission (≥161.5, 96.5 to <161.5, <96.5) we observed a stepwise increase in intubation rates (P=0.0034) and mortality rates (P=0.031). CONCLUSIONS: As inflammation, ARDS severity and longer NIV duration prior to ICU are associated with intubation and mortality rates, prognosis appears to be largely determined by disease severity. Whether NIV aggravates ARDS or if it indicates lack of recovery independent from type of ventilation, or both should be clarified in a prospective trial.