Large-scale studies link preoperative cognition to delirium risk, reveal its deadly toll after surgery

Editor's Note

Older surgical patients with preoperative cognitive impairment face significantly higher odds of developing postoperative delirium (POD), and POD itself is tied to markedly worse surgical outcomes, according to two major studies published July 2025. Together, the findings point to delirium as both a high-impact and potentially modifiable target for perioperative quality improvement.

As reported in MedComm, a multicenter Chinese cohort study analyzed 2,257 patients aged 75 and older undergoing elective noncardiac, noncranial surgery. Preoperative Mini-Cog testing found 28.4% had cognitive impairment, which doubled their POD risk (adjusted OR, 1.74; 95% CI, 1.28–2.36). The association held after adjusting for demographic, preoperative, and intraoperative factors, and across propensity score–matched groups. Incidence rose nearly linearly as Mini-Cog scores declined. Complementary Mendelian randomization using European genetic data suggested a possible causal link: higher cognitive performance was associated with reduced delirium risk (OR, 0.74; 95% CI, 0.59–0.93). The authors note brief cognitive screening could help flag high-risk patients for targeted preventive strategies.

A separate JAMA Network analysis of more than 5.5 million US Medicare admissions for major noncardiac surgery found POD in 3.6% of cases. After risk adjustment, POD was associated with 3.5-fold higher odds of death or major complications, 2.8-fold higher odds of 30-day mortality, and 4.0-fold higher odds of nonhome discharge. Rates varied nearly threefold between hospitals even after controlling for patient risk. Patients in hospitals with high prior-year POD rates had 46% higher odds of developing it, while those in low-rate hospitals had roughly half the odds.

Both studies highlight the burden of POD, which prior research links to longer hospital stays, cognitive decline, and higher costs. The Chinese cohort shows preoperative cognition as a strong, independent predictor, suggesting screening could guide preventive interventions such as optimizing anesthesia management, enhancing postoperative orientation, and supporting sensory and mobility needs. The US national data show POD’s association with adverse outcomes and wide variation across institutions, suggesting hospital-level practices may meaningfully influence risk.