Predisposing and Precipitating Factors for Delirium in the Very Old (≥80 Years): A Prospective Cohort Study of 3,076 Patients.

BACKGROUND Predisposing and precipitating factors for delirium for the elderly, over the age of 65 years, are known, but not for the very old, over 80 years. As the society is getting older and evermore patients will reach >80 years, more evidence of the factors and their contribution to delirium is required in this patient group. METHODS In the course of 1 year, 3,076 patients above 80 years were screened prospectively for delirium based on a Delirium Observation Screening (DOS) scale, Intensive Care Delirium Screening Checklist (ICDSC), and a DSM (Diagnostic and Statistical Manual)-5 nursing instrument (ePA-AC) construct. Relevant predisposing and precipitating factors for delirium were assessed with a multiple regression analysis. RESULTS Of 3,076 patients above 80 years, 1,285 (41.8%) developed a delirium, which led to twice prolonged hospitalization (p < 0.001), requirement for subsequent assisted living (OR 2.2, CI: 1.73-2.8, p < 0.001), and increased mortality (OR 24.88, CI: 13.75-45.03, p < 0.001). Relevant predisposing factors were dementia (OR 15.6, CI: 10.17-23.91, p < 0.001), pressure sores (OR 4.61, CI: 2.74-7.76, p < 0.001), and epilepsy (OR 3.65, CI: 2.12-6.28, p < 0.0001). Relevant precipitating factors were acute renal failure (4.96, CI: 2.38-10.3, p < 0.001), intracranial hemorrhage (OR 8.7, CI: 4.27-17.7, p < 0.001), and pleural effusions (OR 3.25, CI: 1.77-17.8, p < 0.001). CONCLUSION Compared to the general delirium rate of approximately 20%, the prevalence of delirium doubled above the age of 80 years (41.8%) due to predisposing factors uncommon in younger patients.