Early Onset Delirium During Hospitalization Increases In-Hospital and Postdischarge Mortality in COVID-19 Patients: A Multicenter Prospective Study

Objective: Delirium is a common feature in COVID-19 patients. Although its association with in-hospital mortality has previously been reported, data concerning postdischarge mortality and delirium subtypes are scarce. We evaluated the association between delirium and its subtypes and both in-hospital and postdischarge mortality. Methods: This multicenter longitudinal clinical-based study was conducted in Monza and Brescia, Italy. The study population included 1,324 patients (median age: 68 years) with COVID-19 admitted to 4 acute clinical wards in northern Italy during the first pandemic waves (February 2020 to January 2021). Delirium within 48 hours of hospital admission was assessed through validated scores and/or clinically according to DSM-5 criteria. The association of delirium—and its subtypes—with in-hospital and postdischarge mortality (over a median observation period of 257 [interquartile range: 189–410] days) was evaluated through Cox proportional hazards models. Results: The 223 patients (16.8%) presenting delirium had around 2-fold increased in-hospital (hazard ratio [HR] = 1.94; 95% CI, 1.38–2.73) and postdischarge (HR = 2.01; 95% CI, 1.48–2.73) mortality than those without delirium. All delirium subtypes were associated with greater risk of death compared to the absence of delirium, but hypoactive delirium revealed the strongest associations with both in-hospital (HR=2.03; 95% CI, 1.32–3.13) and postdischarge (HR=2.22; 95% CI, 1.52–3.26) mortality. Conclusions: In patients with COVID-19, early onset delirium is associated not only with in-hospital mortality but also with shorter postdischarge survival. This suggests that delirium detection and management are crucial to improving the prognosis of COVID-19 patients.