Delirium is a common complication that occurs in various medical conditions. Development of delirium during admission is associated with an increase in length of hospital stay, complication rates, mortality and consequently higher healthcare expenditures. Besides these short-term consequences, delirium is detrimental to long-term outcome with an ensuing higher risk of dementia, institutionalization and death.
Development of delirium is associated with increasing age. The risk for postoperative delirium among elderly patients ranges from 4%-53%. Incidence differs between different surgical procedures and between emergency or elective surgery. A systematic review comparing general to regional anaesthetic procedures did not show significant differences in the risk for developing postoperative delirium.
Although an array of risk factors associated with development of delirium has been identified in numerous studies, validated models predicting delirium in individual patients are scarce.
Moreover, existing models tend to focus on demographic characteristics and comorbid conditions exclusively. Models predicting development of delirium by using individual pathophysiological markers involved in the evolution of delirium are absent.
Previous research has suggested that impairment of attentional function might serve as an early and specific individual predictor of incident delirium, even in previously cognitively undisturbed patients. So far only one study has prospectively assessed preoperative intra-individual reaction time variability as a predictor of postoperative delirium. This study was limited to elderly (age 70 years or older) patients undergoing elective hip and knee replacement and did not examine confounding factors such as preoperative use of (anti-cholinergic) drugs, preoperative presence of symptoms of depression, cognitive decline or impairment in activities of daily living making. Although this study showed significant higher preoperative intra-individual reaction time variability among patients developing postoperative delirium, no attempts to reproduce these findings in other surgical populations have been published to date, limiting external validity and practical implementation of these observations.
The investigators hypothesize that preoperative intra-individual reaction-time variability is an independent predictor of postoperative delirium. In this study the investigators aim at assessing the potential of preoperative administration of a short test of attentional function in predicting postoperative delirium in a population of elderly non-dementia patients undergoing major elective surgery. Utilization of a test measuring attentional function in a clinically easy-to-use tool could potentially yield a pathophysiological monitor to preoperatively identify individual patients undergoing elective surgery who are at an increased risk of evolving delirium and create a target for future prophylactic treatment.
