Delirium in older COVID‐19 patients: Evaluating risk factors and outcomes

OBJECTIVES: A high incidence of delirium has been reported in older patients with Coronavirus disease 2019 (COVID‐19). We aimed to identify determinants of delirium, including the Clinical Frailty Scale, in hospitalized older patients with COVID‐19. Furthermore, we aimed to study the association of delirium independent of frailty with in‐hospital outcomes in older COVID‐19 patients. METHODS: This study was performed within the framework of the multi‐center COVID‐OLD cohort study and included patients aged ≥60 years who were admitted to the general ward because of COVID‐19 in the Netherlands between February and May 2020. Data were collected on demographics, co‐morbidity, disease severity, and geriatric parameters. Prevalence of delirium during hospital admission was recorded based on delirium screening using the Delirium Observation Screening Scale (DOSS) which was scored three times daily. A DOSS score ≥3 was followed by a delirium assessment by the ward physician In‐hospital outcomes included length of stay, discharge destination, and mortality. RESULTS: A total of 412 patients were included (median age 76, 58% male). Delirium was present in 82 patients. In multivariable analysis, previous episode of delirium (Odds ratio [OR] 8.9 [95% CI 2.3–33.6] p = 0.001), and pre‐existent memory problems (OR 7.6 [95% CI 3.1–22.5] p < 0.001) were associated with increased delirium risk. Clinical Frailty Scale was associated with increased delirium risk (OR 1.63 [95%CI 1.40–1.90] p < 0.001) in univariable analysis, but not in multivariable analysis. Patients who developed delirium had a shorter symptom duration and lower levels of C‐reactive protein upon presentation, whereas vital parameters did not differ. Patients who developed a delirium had a longer hospital stay and were more often discharged to a nursing home. Delirium was associated with mortality (OR 2.84 [95% CI1.71–4.72] p < 0.001), but not in multivariable analyses. CONCLUSIONS: A previous delirium and pre‐existent memory problems were associated with delirium risk in COVID‐19. Delirium was not an independent predictor of mortality after adjustment for frailty.