Effects of Coronavirus Disease 2019 and Frailty on Delirium in the Intensive Care Unit: A Propensity Score Analysis

Purpose: The association between frailty and delirium has emerged as a research topic. Neurological symptoms have been reported among patients with coronavirus disease 2019 (COVID-19), but its effects on delirium remain unclear. This study aimed to compare the incidence of delirium between patients with COVID-19 and those without COVID-19, and to evaluate the impact of COVID-19 and frailty on delirium. Methods: This retrospective study included patients aged ≥ 20 years who were admitted to our intensive care unit (ICU) between January 2020 and February 2022. An inverse probability of treatment weighting using stabilized inverse propensity scores was adopted to minimize bias. After patient demographics were adjusted, the incidence of delirium, assessed using the Confusion Assessment Method for ICU, was compared be-tween patients with COVID-19 and those without COVID-19. The effects of COVID-19 and the Clinical Frailty Scale score on delirium were analyzed by adjusting some covariates, including the sequential organ failure assessment (SOFA) score, using a generalized estimating equation. Results: Among 260 eligible patients, 226 patients were included. The weighted incidence of delirium was 56.9% and 61.9% in patients with and without COVID-19, respectively (p = 0.67). The generalized estimating equation revealed that the odds ratios (95% confidence interval) for COVID-19, the CFS score, and the SOFA score were 1.49 (0.62 - 3.57), 1.46 (1.11 - 1.91), and 1.22 (1.10 - 1.36), respectively. Conclusion: CFS and SOFA scores on ICU admission may be associated with delirium, with no significant difference between patients with COVID-19 and those without COVID-19.