Postoperative Delirium

Importance  

The study results suggest that delirium is the most common postoperative complication in older adults and is associated with poor outcomes, including long-term cognitive decline and incident dementia.

Aim  

To examine the patterns and pace of cognitive decline up to 72 months (6 years) in a cohort of older adults following delirium.

Design, environment and participants  

This was a prospective observational cohort study with long-term follow-up that included 560 community-dwelling older adults (aged 70 years and older) in the ongoing Success Aging after Elective Surgery study that began in 2010. Data were analyzed from 2021 until 2022.

Exposure  

Development of incident delirium after elective major surgery.

Main results and measures  

Delirium was assessed daily during hospitalization using the confusion assessment method, which was complemented by chart review. Cognitive performance was assessed using a comprehensive battery of neuropsychological tests preoperatively and at multiple time points postoperatively through 72 months of follow-up.

We assessed longitudinal cognitive change using a composite measure of neuropsychological performance called general cognitive performance (GCP), which is scaled so that 10 points on the GCP equal 1 population SD. The effects of the retest were adjusted using the results of cognitive tests in a nonsurgical comparison group.

Results 

The 560 participants (326 women [58%]; mean [SD] age, 76.7 [5.2] years) provided a total of 2637 person-years of follow-up. One hundred thirty-four participants (24%) developed postoperative delirium.

Cognitive change after surgery was complex: we found evidence of differences in acute, subsequent short-term, intermediate, and long-term change from the time of surgery that were associated with the development of postoperative delirium.

Long-term cognitive change, which adjusted for practice and recovery effects, occurred at a rate of about -1.0 GCP units (95% CI, -1.1 to -0.9) per year (about 0.10 SD units of the population per year).

Participants with delirium showed significantly faster long-term cognitive change with −0.4 additional GCP units (95% CI, −0.1 to −0.7) or −1.4 units per year (about 0 .14 ​​SD units of the population per year).

Conclusions and relevance  

This cohort study found that delirium was associated with a 40% acceleration in the slope of cognitive decline up to 72 months after elective surgery. Because this is an observational study, we cannot be sure whether delirium directly causes subsequent cognitive decline or whether patients with preclinical brain disease are more likely to develop delirium. Future research is needed to understand the causal pathway between delirium and cognitive impairment.

Comments

Study highlights importance of delirium prevention to preserve brain health in older adults undergoing surgery

Research published in JAMA Internal Medicine finds that the development of postoperative delirium is associated with a 40% faster rate of cognitive decline than those who do not develop delirium.

"Delirium is associated with more rapid cognitive decline," said Zachary J. Kunicki, PhD, MS, MPH Assistant Professor located at the Warren Alpert Medical School of Brown University, the first author. "Whether delirium causes this faster rate of decline or is simply a marker of those at risk of experiencing faster rates of decline has yet to be determined."

"This study has the longest follow-up period of any study examining people with delirium after surgery," said Sharon K. Inouye, MD, MPH Director, Aging Brain Center, Hinda and Arthur Marcus Institute for Aging Research, main author and director researcher on the work. “While future studies are needed, this study raises the possibility that delirium may predispose to permanent cognitive impairment and potentially dementia. “This highlights the importance of delirium prevention to preserve brain health in older adults undergoing surgery,” she said.

Delirium is the most common postoperative complication in older adults and is associated with poor outcomes, including long-term cognitive decline and incident dementia.

Richard N. Jones, ScD, Warren Alpert Medical School of Brown University is co-senior author of the article, “Six-year cognitive trajectory in older adults after major surgery and delirium.” Inouye is the overall principal investigator of the SAGES study (NIH Grant No. P01AG031720) that funded this long-term observational study.

The SAGES cohort has followed 560 older adults (ages 70 and older), measuring their cognition every 6 months for 36 months, then annually for up to 6 years. Using a detailed cognitive test battery, composed of 11 different tests, we found that cognitive changes after surgery are complex and that delirium influences each moment. The average cognitive changes observed after surgery include a sharp drop one month after surgery, an increase two months after surgery, a stable period from 6 to 30 months after surgery, and then a steady decline from 3 to 6 months after surgery. years after surgery.

Delirium is associated with a steeper fall at 1 month, a greater recovery at 2 months, and a more rapid decline at all periods from 6 months to 6 years, respectively. The results suggest that delirium itself may contribute to cognitive decline after surgery, or that delirium may serve to identify people at risk for more rapid cognitive decline in the future. Future research will be needed to examine whether either or both of these hypotheses better explain the relationship between delirium and cognitive impairment.

Collaborating institutions are Warren Alpert Medical School of Brown University; Beth Israel Deaconess Medical Center; Harvard Medical School; and the University of Maryland.

The study was funded by Grants Nos. P01AG031720 (SKI), R33AG071744 (SKI/RNJ), R01AG044518 (SKI/RNJ) from the National Institute on Aging.