Incidence of Delirium in Critically Ill Patients With and Without COVID-19

Background It is known that patients with COVID-19 are at high risk of developing delirium. The aim of the study was to compare the incidence of delirium between critically ill patients with and without a diagnosis of COVID-19. Methods This is a retrospective study conducted in a southern Brazilian hospital from March 2020 to January 2021. Patients were divided into two groups: the COVID-19 group consisted of patients with a diagnosis of COVID-19 confirmed by reverse transcription-polymerase chain reaction (RT-PCR) or serological tests who were admitted to specific ICUs. The non-COVID-19 group consisted of patients with other surgical and medical diagnoses who were admitted to non-COVID ICUs. All patients were evaluated daily using the Intensive Care Delirium Screening Checklist (ICDSC). The two cohorts were compared in terms of the diagnosis of delirium. Results Of the 649 patients who remained more than 48 h in the ICU, 523 were eligible for the study (COVID-19 group: 292, non-COVID-19 group: 231). There were 119 (22.7%) patients who had at least one episode of delirium, including 96 (32.9%) in the COVID-19 group and 23 (10.0%) in the non-COVID-19 group (odds ratio [OR] 4.42; 95% confidence interval [CI], 2.69 to 7.26; p < 0.001). Among patients mechanically ventilated for two days or more, the incidence of delirium did not differ between groups (COVID-19: 89/211, 42.1% vs non-COVID-19: 19/47, 40.4%; p = 0.82). Logistic regression showed that the duration of mechanical ventilation was the only independent factor associated with delirium (p = 0.001). Conclusion COVID-19 can be associated with a higher incidence of delirium among critically ill patients, but there was no difference in this incidence between groups when mechanical ventilation lasted two days or more.