Study explores risk factors for postoperative delirium

By Dr. Priyom Bose, Ph.D.Aug 15 2023Reviewed by Sophia Coveney

The number of elderly and middle-aged orthopedic patients is on the rise and postoperative delirium (POD) is an increasingly common complication in fracture patients belonging to this age group.

Motivated by this phenomenon, a new Scientific Reports study aimed to investigate the risk factors and incidence rates of POD in elderly and middle-aged patients with fractures. Middle-aged and elderly patients were defined to be individuals who were 50 years of age or older.

Background

The onset of POD is normally 2–3 days post-operation, and in patients older than 65 years, the incidence is between 5-50%. This could lead to serious consequences, such as permanent dementia or even death.

Currently, many challenges exist related to the diagnosis and treatment of POD. Most notably, there is a lack of effective drug therapies. It is, therefore, crucial to target patients at high-risk early, so that the incidence of POD can be prevented and the duration of delirium can be shortened.

Knowledge of the risk factors leading to POD is still limited, given that its pathophysiological mechanism is unclear. Therefore, it is crucial to develop deeper insights into the risk factors of POD to reduce its incidence and develop effective treatment strategies.

About the study

In this study, clinical data on 648 middle-aged and elderly fracture patients was retrospectively analyzed. These patients underwent surgical treatment between January 2018 and December 2020. The age range was 50–103 years with a mean of 70 years.

The incidence of postoperative delirium was analyzed. To screen risk factors related to age, gender, preoperative complications, anesthesia method, operation time, the interval between injury and operation, hidden blood loss and hormone use, and intraoperative blood loss, a univariate analysis was used.

To determine the main independent risk factors, multivariate logistic regressions were estimated.

Key findings

Out of 648 patients, 115 had POD (17.74%). It was observed that the risk of POD in patients aged 70 years or more was much higher than that in patients aged less than 70 years.

This could be explained by the fact that with age, the body functions deteriorate and the ability to adapt to external stress decreases, especially for surgery and fracture trauma. It could also be related to cortical function decline, cholinergic nerve decline in the brain, or the gradual diminishing of central cholinergic neurons and acetylcholine.

Additionally, the univariate analysis showed that POD had a significant correlation with disease comorbidity. Elderly and middle-aged patients often have other health complications, such as high blood pressure, high blood sugar, and high blood lipid.

This can lead to reduced immunity, the ability to manage stress, acid-base imbalance, and postoperative hypoxemia, which could lead to POD. Research has shown that preoperative underlying diseases are related to POD, and the risk is significantly higher for patients with pulmonary diseases and Alzheimer’s disease.

The study also found an association of POD with the length of bed rest and type of surgery. The findings documented here are consistent with prior research that showed that the risk of POD is significantly higher after hip and spine surgery. This could be due to patients requiring bed rest for prolonged periods after such surgeries.

The incidence of POD in general anesthesia patients was found to be significantly higher than in those with local anesthesia. It is therefore recommended that for elderly and middle-aged fracture patients, much attention should be paid to the management of surgery and anesthesia.

Surgical methods with short time and less trauma should be selected, and the normal physiological functions of the body should be left undisturbed as much as possible. Anesthesia should also be simple and if required, electroencephalogram monitoring should be used to avoid anesthesia being too deep.

There is no consensus on the effect of hormonal use on POD occurrence. Here, no significant effect of short-term use of small amounts of methylprednisolone was noted in patients with burst spine fractures and hip fractures on reducing the occurrence of POD.

It was, however, noted that the risk of POD was significantly higher in operations with high perioperative blood loss such as spine and hip surgery.

Conclusions

Since this was a retrospective analysis, the inclusion and exclusion criteria for patients with POD could be biased. In addition, the data was obtained from a single clinical center. In the future, the mechanisms and influencing risk factors should be further explored in multicenter, large-sample-size studies.

In sum, advanced age, medical comorbidities, complex surgeries, general anesthesia, and greater perioperative blood loss were observed to be independent risk factors of POD in elderly and middle-aged patients with fractures. In such patients, more comprehensive perioperative management and less surgical trauma could significantly reduce the incidence of POD.