Surgery, Anesthesia Not Linked to Long-Term Cognitive Impairment in Older Adults

“Postoperative confusion does not mean there is long-term dementia because of the operation. The result is a significant finding. Many patients and providers discourage surgery in the elderly based on old data. Our techniques are now so improved that this study of 8,500 operated cases with general anesthesia found are no increased incidence of cognitive impairment in the Denmark. Research of this type from the Scandanavian countries has extra validly with me because they can track their patients more carefully. Patients return for follow-up care as directed better than in American” Bill Chesnut, MD

AAOS Now online edition _March 1, 2016  __SOURCE: American Society of Anesthesiologists

CHICAGO — March 1, 2016 — New research suggests that older patients should not feel reluctant to have quality of life enhancing surgeries due to concerns that undergoing anaesthesia may boost their risk of developing cognitive issues.

In a study of more than 8,500 middle-aged and elderly Danish twins published in Anesthesiology, researchers found no clinically significant association between major surgery and general anaesthesia with long-term cognitive decline.

“Our use of twins in the study provides a powerful approach to detect subtle effects of surgery and anaesthesia on cognitive functioning by minimising the risk that the true effects of surgery and anaesthesia are mixed-up with other environmental and genetic factors,” said lead author Unni Dokkedal, MD, University of Southern Denmark, Odense, Denmark. “We found no significant cognitive effects related to surgery and anaesthesia in these patients, suggesting that other factors, such as preoperative cognitive levels and underlying diseases, are more important to cognitive functioning in aging patients following surgery.”

The researchers examined the association between exposure to surgery and level of cognitive functioning in a sample of 4,299 middle-aged twins aged younger than 70 years and 4,204 elderly twins aged 70 years or older.

Results from cognitive tests of twins who had either major, minor, hip, and knee replacement or other surgery within 18 to 24 years before cognitive examination were compared with the cognitive results of a reference group, comprised of twins who had no surgical procedures. Test results were also compared in an intra-pair analysis of twins, one of whom was exposed to surgery while the other was not, to assess genetic and shared environmental confounding.

Twins who had undergone major surgery had slightly lower cognitive scores, compared with the reference group, but when compared to their twin, when genetic and shared environmental factors were adjusted, no association was observed.

Interestingly, twins who had undergone hip and knee replacement surgery had slightly higher cognitive scores, but the difference was not statistically significant.

No differences were found in the minor or other surgery group when compared with the reference group.

The authors also analysed data for patients who had undergone surgery from 3 months to 2 years before cognitive examination and found no effect of the short time interval between surgery and cognitive examination on cognitive function.

The results suggest preoperative cognitive functioning and underlying diseases are more important for cognitive functioning in mid- and late life than surgery and anaesthesia.

“It is important to know whether surgery and anaesthesia have any negative effects, especially with regard to preoperative counselling of the patient,” said Dr. Dokkedal. “This research has the potential to become a key piece of this very complex research puzzle.”

In an accompanying editorial, Michael S. Avidan, MD, and Alex S. Evers, MD, Washington University School of Medicine, St. Louis, Missouri, wrote: “On the basis of a growing body of evidence, of which the study by Dokkedal et al is symbolic, older patients should today be reassured that surgery and anaesthesia are unlikely to be implicated in causing persistent cognitive decline or incident dementia. The large number of patients and the use of rigorous longitudinal cognitive testing in the study increased the reliability of the findings.”