Cognitive-frailty phenotyping and postoperative delirium risk in older surgical patients: a retrospective cohort study.

Background

Postoperative delirium remains a common complication in older surgical patients. Frailty and cognitive impairment are established risk factors but are often assessed independently. We examined whether a pragmatic 2×2 cognitive-frailty phenotype framework stratifies postoperative delirium risk.

Methods

This retrospective cohort study included patients aged ≥70 yr undergoing elective noncardiac, noncranial surgery at a tertiary centre from February 2022 to July 2024. Cognition and frailty were assessed using the Mini-Cog and Clinical Frailty Scale. Patients were classified into four phenotypes: intact, frail-only, cognitive-only, and cognitive-frailty. POD was assessed using the 4A's Test (4AT) in the PACU on the day of surgery and in surgical wards on postoperative days 1 and 2. The primary outcome was overall postoperative delirium, defined as at least one positive 4AT assessment. The secondary outcome was postoperative length of stay (LOS).

Results

Among 3353 patients, 61% were intact, 20% frail-only, 11% cognitive-only, and 8% cognitive-frailty. Overall postoperative delirium incidence was 7.5%, increasing from 4.2% in the intact to 24.0% in the cognitive-frailty phenotype (P<0.001). Compared with intact, postoperative delirium risk was highest in the cognitive-frailty phenotype (adjusted odds ratio [aOR] 4.79, 95% confidence interval [CI] 3.22-7.11), followed by the cognitive-only phenotype (aOR 2.41, 95% CI 1.60-3.63) and the frail-only phenotype (aOR 1.72, 95% CI 1.20-2.47). Median postoperative LOS increased from 2.6 to 4.5 days across phenotypes (P<0.001).

Conclusions

In this cohort of older surgical patients, a pragmatic two-dimensional cognitive-frailty framework based on bedside screening tools demonstrated a clear gradient in postoperative delirium risk. This might support perioperative risk stratification, preventive strategies, and future research.