Epidemiology and risk factors for delirium across hospital settings

Abstract

Delirium is one of the most common causes of acute end-organ dysfunction across hospital settings, occurring in as high as 80% of critically ill patients that require intensive care unit (ICU) care. The implications of this acute form of brain injury are profound. Across many hospital settings (emergency department, general medical ward, postoperative and ICU), a patient who experiences delirium is more likely to experience increased short- and long-term mortality, decreases in long-term cognitive function, increases in hospital length of stay and increased complications of hospital care. With the development of reliable setting-specific delirium-screening instruments, researchers have been able to highlight the predisposing and potentially modifiable risk factors that place patients at highest risk. Among the large number of risk factors discovered, administration of potent sedative medications, most notably benzodiazepines, is most consistently and strongly associated with an increased burden of delirium. Alternatively, in both the hospital and ICU, delirium can be prevented with the application of protocols that include early mobility/exercise. Future studies must work to understand the epidemiology across settings and focus upon modifiable risk factors that can be integrated into existing delirium prevention and treatment protocols.

Fig. 1

Adapted from Vasilevskis et al. the ABCDE is an ICU-acquired delirium and weakness mitigation strategy for the critically ill patient. This strategy is a protocolized bundle performed daily on mechanically ventilated and/or sedated patients in the ICU. ABCDE = Awakening and Breathing Coordination, Choice of sedation, Delirium monitoring and management, and Early mobility/exercise. Adapted from: Vasilevskis EE et al. ICU-acquired delirium and weakness – Crossing the quality chasm. Reproduced with permission from the American College of Chest Physicians. Chest. 2010; 138(5): 1224–1233.

Fig. 2

The interrelationship between patient vulnerability and precipitating factors in the development of delirium. Low-level vulnerability requires high-level noxious stimuli to develop delirium (black arrow). High-level vulnerability requires low-level noxious stimuli to develop delirium (gray arrow).