Factors associated with the severity of delirium.

Background: Various factors affecting the development of delirium have been identified. However, the associations between the severity of delirium and potentially related factors have not been adequately investigated. The aim of the present study was to explore factors associated with the severity of delirium and to identify the reversible contributing factors.

Methods: A total of 577 patients with delirium referred to the Department of Psychiatry during the 5 years from May 2015 to April 2020 at a general hospital were included. The Delirium Rating Scale-revised-98 (DRS-R-98) was used to measure the severity of delirium. Multiple regression analysis was used to determine whether individual factors were associated with the severity of delirium.

Results: Intensive care unit admission (p = 0.003), use of benzodiazepines (p = 0.01), dementia (p = 0.02), and older age (p = 0.045) were all positively associated the severity of delirium, while use of β-blockers (p = 0.001) was negatively associated with the severity of delirium.

Conclusions: Reversible contributing factors, that is use of benzodiazepines, should be avoided as much as possible, especially in elderly patients or patients with dementia or patients who need critical care in ICU. Reducing the dose of benzodiazepines or switching them to other drugs should be a priority.