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

Abstract

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.

Objective: To 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 participants: This 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.

Exposure: Development of incident delirium following major elective surgery.

Main outcomes and measures: Delirium 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.

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 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 relevance: This 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.

Figure.. General Cognitive Performance (GCP) Trajectory by Delirium Status

Delirium is the solid line surrounded by the 95% CI in blue shading; no delirium is represented in the solid line surrounded by the 95% CI in orange shading. Solid light blue reference lines indicate the baseline level of GCP. A, Association between estimated GCP composite scores, which were derived from the components of change model, and years since surgery. The GCP estimates were adjusted for age, sex, race, Informant Questionnaire on Cognitive Decline in the Elderly at preoperative baseline, any instrumental activities of daily living impairment at baseline, Geriatric Depression Scale scores, Charlson Comorbidity Index scores, and surgery type. B, Same association, except the starting point is not offset by the mean difference in baseline GCP scores.