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New data indicates a connection between post-surgery cognitive declines and delirium, though future research may be needed to understand the causal pathway.
Delirium—older adults’ most common postoperative complication—is associated with a cognitive decline acceleration of 40% out to 72 months after an elective surgery, according to new findings.1
This research into community-dwelling adults over 70 years of age came as a result of the greater recognition of delirium’s link to higher risk for long-term cognitive decline and dementia, and the need for more insight on the topic.2,3 The research was authored by Zachary J. Kunicki, PhD, MS, MPH, from the Department of Psychiatry and Human Behavior at Warren Alpert Medical School, Brown University.
Kunicki and colleagues noted the previous Successful Aging after Elective Surgery (SAGES) study’s findings that patients with postoperative delirium showed greater long-term declines in cognition out to 36 months compared with those without delirium.4
“In the present study, we extended our prior work to evaluate the long-term cognitive trajectory to 72 months (6 years) following postoperative delirium,” Kunicki and colleagues wrote. “We hypothesized that delirium would be associated with an accelerated pace of cognitive decline to 72 months.”
The investigators analyzed data from 2021 - 2022, conducting an observational, prospective cohort study on 560 adult participants over 70 and living in communities from the ongoing SAGES study that was started in 2010. The study involved 560 participants, 58% of which were female, and the participants had a mean [SD] age of 76.7 [5.2] years, and they all provided a total of 2637 person-years of follow-up.
In order to assess the associations between repeated cognitive assessments and learning, a comparison group consisting of 119 participants who did not undergo surgery was added to the study by the investigators
These study participants were recruited from primary care outpatient settings and underwent the same group of neuropsychological tests as did the surgical cohort at baseline. They were then followed up at 1, 2, 6, 18, and 36 months from enrollment.
During hospitalization, delirium was evaluated by the investigators daily using the Confusion Assessment Method, which was supplemented by a review of the patient's medical records. A comprehensive battery of neuropsychological tests was given before surgery and multiple times up to 72 months after surgery to assess cognitive performance.
The research team used general cognitive performance (GCP), a composite measure of neuropsychological performance, to evaluate longitudinal cognitive changes. The team scaled GCP such that 10 points on the GCP equated to 1 population standard deviation, and cognitive test results from a nonsurgical comparison group were used to adjust for retest effects.
Of the 560 participants, 24% of them were found by the team to have developed postoperative delirium, and the research team found that cognitive change following surgery was a complex process, with differences in acute, post-short-term, intermediate, and longer-term changes associated with development of postoperative delirium.
The long-term cognitive change occurred at a pace of approximately -1.0 GCP units (95% CI, -1.1 to -0.9) per year (around 0.10 population SD units per-year), after adjusting for practice and recovery effects.
The investigators noted that participants who had delirium then showed substantially faster long-term cognitive changes. They had an additional -0.4 GCP units (95% CI, -0.1 to -0.7), or -1.4 units per year (about 0.14 population SD units per year).
“The results of this cohort study are consistent with either the hypothesis that delirium itself is a risk factor for accelerated cognitive decline after surgery, or with the hypothesis that delirium serves as a marker of those with underlying brain vulnerability (eg, cognitive decline before surgery) who are at heightened risk for accelerated postoperative cognitive decline,” the team wrote.