Clinical Characteristics and Mortality-Associated Factors in COVID-19 Critical Patients in a Portuguese ICU

Introduction: Severe COVID-19 is associated with serious complications and poor outcomes. Older age and underlying comorbidities are known risk factors for severe COVID-19, but a better understanding of baseline characteristics and outcomes of patients with severe COVID-19 is urgently needed.

Methods: This study was a retrospective case series of 227 consecutive patients with laboratory-confirmed COVID-19 admitted to the intensive care unit (ICU) at our institution between March 2020 and December 2021. Demographic and clinical data were collected.

Results: The median age of patients was 65 years, and 180 (79.3%) were male. Cardiovascular comorbidities were frequent and included hypertension (n=148; 65.2%), dyslipidemia (n=116; 51.1%), obesity (n=114; 50.2%), and diabetes mellitus (n=80; 35.2%). About 20% of the patients had the chronic respiratory disease, with sleep apnea being the most common. Immunosuppression was identified in 13% of the patients, with autoimmunity, post-transplantation, and neoplasms being the most represented causes. Most patients were admitted to the ICU at six to 15 days after symptom onset, corresponding to stages IIb (pulmonary involvement/hypoxia) and III (hyperinflammatory). All patients received systemic steroids, with an average treatment duration of 22 days. Several ventilatory support strategies were used; 80 patients were supported entirely noninvasively with high flow nasal oxygenation and noninvasive ventilation, while 164 patients were invasively ventilated. Most intubations (65%) occurred in the first 24 hours after admission, and the mean duration of mechanical ventilation was 14 days. The reintubation rate was 10%, occurring on average two to three days after planned extubation. Thirty-two tracheostomies were performed. Bacterial co-infection was treated in 75% of patients, and Aspergillus co-infection complicating COVID-19 pneumonia was diagnosed in eight patients. Median ICU and hospital stays were 15 and 25 days, respectively, and the 28-day mortality rate was 38%. Patients over 75 years experienced a higher mortality rate (56%). Increased age and multimorbidity, particularly comprising cardiovascular disease and associated risk factors, were significantly more common in patients who died within 28 days after ICU admission.

Conclusions: A large proportion of critically ill COVID-19 patients required prolonged mechanical ventilation. ICU/hospital stay and mortality were particularly elevated in older patients and patients with cardiovascular risk factors. Considerable discrepancy existed between the proportion of patients with microbiological documentation of bacterial infections and those receiving antimicrobials. Improved methods for adequate microbiological diagnosis are needed and stewardship programs should be reinforced.