Development and validation of a delirium risk assessment tool in older patients admitted to the Emergency Department Observation Unit

Background: Delirium is frequent though undetected in older patients admitted to the Emergency Department (ED). Aims: To develop and validate a delirium risk assessment tool for older persons admitted to the ED Observation Unit (OU). Methods: We used data from two samples of 65 + year-old patients, one admitted to the ED of Brescia Hospital (n = 257) and one to the ED of Desio Hospital (n = 107), Italy. Data from Brescia were used as training sample, those collected in Desio as testing one. Delirium was assessed using the 4AT and patients’ characteristic were retrieved from medical charts. Variables found to be associated with delirium in the training sample were tested for the creation of a delirium risk assessment tool. The resulting tool’s performances were assessed in the testing subsample. Results: Of all possible scores tested, the combination with the highest discriminative ability in the training sample included: age ≥ 75 years, dementia diagnosis, chronic use of neuroleptics, and hearing impairment. The delirium score exhibited an AUC of 0.874 and 0.893 in the training and testing samples, respectively. For a 1-point increase in the score, the odds of delirium increased more than twice in both samples. Discussion: We propose a delirium risk assessing tool that includes variables that can be easily collected at ED admission and that can be calculated rapidly. Conclusion: A risk assessment tool could help improving delirium detection in older persons referring to ED.