Preoperative Delirium: Not to Be Overlooked

Abstract

To the Editor We read with interest the article by Gottschalk et al.1 and the accompanying editorial2 on the occurrence of delirium after hip fracture surgery. We would like to make a brief comparison to the relevant results of an audit on the occurrence of postoperative delirium that was completed on 27 hip fracture patients between July and August 2015 at our hospital, a tertiary referral center for femoral neck fractures in Brisbane, Australia. Our IRB granted us written permission to publish the results of this audit. Our hospital repairs >200 hip fractures a year, employing a multidisciplinary care model comprising a team of orthogeriatricians, anesthesiologists, and orthopedic surgeons. Our patients are routinely transferred to orthopedic ward after surgery with special nursing care, if warranted. We assessed delirium using 4AT,a a simple and brief screening tool that has been validated for use in elderly inpatients.3 The first assessment was performed within 24 hours before surgery. Postoperative assessment was conducted during the first 5 postoperative days. We diagnosed delirium in 11 (41%) of our patients when a 4AT score of ≥4 was recorded on any of the first 5 postoperative days. Ten (37%) of our patients had history of cognitive impairment. Of these 10 patients, 6 (60%) developed preoperative delirium. Five of 6 patients with preoperative delirium developed postoperative delirium. Five of 7 patients who were delirious on the second postoperative day had preoperative delirium. Cognitive impairment is a significant predictor for preoperative delirium,4 so it follows that excluding preoperative delirium from a patient sample runs the risk of excluding considerable proportion of those with preoperative cognitive impairment from analysis. Although our sample is too small to draw conclusions, we agree with the editorial observation that patients with preoperative delirium must be included to avoid underestimating the true extent of the problem. In addition, we note that, by excluding patients with existing delirium, the observation of a lack of association with long-term mortality is only valid in relation to incident delirium recorded on the second postoperative day and not to delirium in general. Preoperative delirium, especially the new-onset delirium associated with fracture, should be given importance as a separate entity,5 so that efforts can be taken to modify preventable factors that could contribute toward postoperative delirium. In our audit, we found that the peak in the number of delirious patients occurred on postoperative day 2. The number tapered toward day 4 but increased on day 5. This biphasic response may indicate an initial trend toward the resolution of surgical or anesthetic effects. The increase on day 5 may possibly be related to other causes for delirium.6 However, our numbers are too small to provide anything more than an interesting observation that invites speculation. We congratulate the investigators for their longitudinal study on this major issue. Many previous studies on hip fracture dealt with short-term mortality.7 A similar study8 on elderly delirious patients showed that delirium is associated with an increased mortality risk for at least 5 years, possibly because of the decompensation inflicted on patients by delirium itself. Usha Gurunathan, MBBS, MD, M Epi, FANZCAKurichi Marudhachalam, MBBS, DA, MD, DNB, FCARCSI, FRCA, FANZCAKit Reynolds, BA (MBBS)Department of Anesthesia and Perfusion ServicesThe Prince Charles HospitalUniversity of QueenslandBrisbane, Australia[email protected]