Six-Year Cognitive Trajectory in Older Adults Following Major Surgery and Delirium

Key PointsQuestionWhat are the patterns and pace of cognitive decline in older adults (older than 70 years) up to 72 months following postoperative delirium? FindingsIn this prospective cohort study of 560 older adults who underwent major elective surgery and developed delirium, cognitive decline during a period of 72 months, adjusted for practice and recovery effects, occurred at a rate of 0.14 population SD units per year. This was significantly faster than the long-term cognitive decline of 0.10 population SD units per year in those who either did not develop delirium or did not undergo surgery. MeaningDelirium was associated with accelerated cognitive decline that continued for 72 months following the index delirium episode; it remains uncertain if delirium causes subsequent cognitive decline or if persons with preclinical brain disease are more likely to develop delirium. ImportanceThe 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. ObjectiveTo examine the patterns and pace of cognitive decline up to 72 months (6 years) in a cohort of older adults following delirium. Design, Setting, and ParticipantsThis was a prospective, observational cohort study with long-term follow-up including 560 community-dwelling older adults (older than 70 years) in the ongoing Successful Aging after Elective Surgery study that began in 2010. The data were analyzed from 2021 to 2022. ExposureDevelopment of incident delirium following major elective surgery. Main Outcomes and MeasuresDelirium was assessed daily during hospitalization using the Confusion Assessment Method, which was supplemented with medical record review. Cognitive performance using a comprehensive battery of neuropsychological tests was assessed preoperatively and across multiple points postoperatively to 72 months of follow-up. We evaluated longitudinal cognitive change using a composite measure of neuropsychological performance called the general cognitive performance (GCP), which is scaled so that 10 points on the GCP is equivalent to 1 population SD. Retest effects were adjusted using cognitive test results in a nonsurgical comparison group. ResultsThe 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 following surgery was complex: we found evidence for differences in acute, post-short-term, intermediate, and longer-term change from the time of surgery that were associated with the development of postoperative delirium. Long-term cognitive change, which was adjusted for practice and recovery effects, occurred at a pace of about -1.0 GCP units (95% CI, -1.1 to -0.9) per year (about 0.10 population SD units per year). Participants with delirium showed significantly faster long-term cognitive change with 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). Conclusions and RelevanceThis cohort study found that delirium was associated with a 40% acceleration in the slope of cognitive decline out to 72 months following 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 decline. This cohort study examines the patterns and pace of cognitive decline up to 72 months in a cohort of older adults following delirium.

Automated summary

This prospective cohort study examined the patterns and pace of cognitive decline up to 72 months following postoperative delirium in older adults. The study found that there was an accelerated cognitive decline rate of 0.14 population SD units per year in those who developed delirium after surgery, compared to the long-term cognitive decline rate of 0.10 population SD units per year in those who did not develop delirium or did not undergo surgery. Delirium was associated with continued cognitive decline for 72 months, but it remains uncertain whether delirium causes subsequent cognitive decline or if individuals with preclinical brain disease are more susceptible to delirium.