Adult patients who are critically ill have a higher likelihood of death when they are ill with COVID-19 vs influenza, according to a study in the Journal of Infection.
Investigators compared clinical characteristics and outcomes of patients critically ill with COVID-19 with a historical patient cohort admitted to an intensive care unit (ICU) for influenza pneumonia, with use of the French administrative health care database, Système National des Données de Santé (SNDS).
Participants with COVID-19 had been hospitalized in French ICUs from March 1, 2020, to June 30, 2021, and had data available for the complete hospital course. The comparative group with influenza included all adult patients hospitalized in an ICU from January 1, 2014, to December 31, 2019. Vaccination status was obtained for patients admitted after January 1, 2021.
The study included 105,979 patients with COVID-19 (median age, 67 years [range, 57-76 years]; 64% male) and 18,763 patients with influenza (median age, 68 [58-78] years; 56% male) admitted to ICUs in France. Patients with COVID-19 had a median Simplified Acute Physiology Score (SAPS) II score at ICU admission of 32 (range, 24-41) vs 39 (range, 29-52) in those with influenza.
Despite younger age and lower SAPS II score, critically ill COVID-19 patients had a longer hospital stay and higher mortality than patients with influenza.
The investigators found patients with influenza more frequently received invasive mechanical ventilation (47% vs 34%, P <.001). The Fine-Gray model showed that COVID-19 was associated with a reduced likelihood of treatment with invasive mechanical ventilation (adjusted subdistribution hazard ratio [aSHR], 0.87; 95% CI, 0.85-0.89) and an increased likelihood of death without invasive mechanical ventilation (aSHR, 2.40; 95% CI, 2.24-2.57), after adjustment for age, sex, comorbidities, and modified SAPS II score at admission.
Patients with COVID-19 were less likely to receive vasopressors (27% vs 40%, P <.001) and renal replacement therapy (RRT) (7% vs. 22%, P <.001) compared with patients with influenza. Among patients who received invasive mechanical ventilation, those with COVID-19 were still less likely to receive vasopressors (74% vs 77%, P <.001) and RRT (18% vs 22%, P <.001) vs those with influenza.
Overall, hospital mortality was increased among patients with COVID-19 compared with those with influenza (25% vs 21%, P <.001), in those who received invasive mechanical ventilation (40% vs 33%, P <.001), and in those who did not receive invasive mechanical ventilation (17% vs 11%, P < .001).
The Fine-Gray model revealed that the likelihood of in-hospital death was greater in patients with COVID-19 (aSHR, 1.69; 95% CI, 1.63-1.75) compared with patients with influenza, particularly in those aged ≥65 years (aSHR, 1.91; 95% CI, 1.83-1.99), after adjustment for age, sex, comorbidities, and modified SAPS II score at admission.
Among patients with invasive ventilation, the ICU length of stay was 18 (range,10-32) days for those with COVID-19 vs 15 (range, 8-26) days in those with influenza (P <.001).
A sensitivity analysis was performed in patients with COVID-19 who were admitted after January 2021 with available vaccine status (n=48,140). After adjustment for age, sex, comorbidities, immunocompromised status, and SAPS-II score at admission, a multivariate model demonstrated that patients with COVID-19 had an increased risk of death vs patients with influenza regardless of vaccination status (COVID-19 nonvaccinated aSHR, 1.73; 95% CI, 1.66-1.80; COVID-19 partially vaccinated: aSHR, 1.79; 95% CI, 1.67-1.93; and COVID-19 fully vaccinated: aSHR, 1.48; 95% CI, 1.26-1.75).
Among several limitations, clinical data such as arterial blood pressure and arterial blood gas were not available in the SNDS, and data were not obtained for pressures on hospital admission or availability of ICU beds. Also, only patients admitted to the ICU were included.
“Despite younger age and lower SAPS II score, critically ill COVID-19 patients had a longer hospital stay and higher mortality than patients with influenza,” even though patients with COVID-19 used less respiratory and hemodynamic supportive care, the study authors concluded.