Low postoperative delirium rates at an urban academic hospital
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Citation
Abstract
INTRODUCTION: Postoperative delirium (POD) is defined as an acute change in the state of mind that is associated with memory loss and behavioral changes after an operation. Although the pathophysiology of postoperative delirium is not fully understood, there are many established factors associated with this altered mental state such as older age, prior history of drug or alcohol abuse, and pre-existing cognitive impairment. Previous literature has reported the rate of POD to be 10% to 15%. Boston Medical Center (Boston, Massachusetts) is an urban accountable care organization (ACO) that provides healthcare for an underserved and often uninsured population, many of whom have chronic disease and substance use disorders and other risk factors for POD. This study aimed to determine the rate of POD at this safety net hospital, anticipating that the rate might be higher than the reported national average.
METHODS: This study had both a prospective arm and a retrospective arm. In the prospective arm, patients were screened (June 2021–December 2021) for eligibility prior to their surgery. On the day of the surgery, eligible patients were approached and consent was obtained. Inclusion criteria were all patients between the ages of 65 and 89 who presented for surgery (non-cardiac, non-neuro) under general anesthesia and required a minimum hospital stay of 3 days. Chart reviews were performed, and Confusion Assessment Method (CAM) scores were recorded by nurses and collected for 3 postoperative days. The retrospective arm of the study analyzed patients who met the same inclusion criteria between the years of 2018 and 2019. CAM scores were collected, and rates of POD were determined for both arms of the study.
RESULTS: A total of 52 patients were enrolled in the prospective arm of the study. Two patients were found to be CAM positive at some point in their postoperative course, giving a rate of POD of 3.85%. The mean age (SD) of CAM-negative patients was 72.0 (5.4) years, whereas the mean age (SD) of CAM-positive patients was 71.2 (3.0) years. The male and female participants were equally represented in both the CAM-positive and CAM-negative cohorts. The only statistically significant finding in the prospective arm was whether the patient was hypernatremic (p = .015). For the retrospective arm of the study, there were a total of 244 patients who fit the same inclusion criteria as used for the prospective arm. Two patients tested positive for delirium, making the rate of POD at 0.82% for this period. The statistically significant variable in the retrospective arm was the hospital length of stay (p = .026).
DISCUSSION: The rate of POD at this urban safety net hospital appears to be much lower than the cited average of 10%–15%. It is possible that POD rates have improved dramatically since the cited averages because of enhanced recovery after surgery (ERAS) protocols and delirium prevention measures. It is also possible that POD is underdiagnosed, especially in non-intensive care unit (non-ICU) settings, where bedside nurses are less familiar with the POD scoring systems. Further research is needed to assess the accuracy of delirium scoring in non-ICU settings.