Older patients with documented preoperative cognitive impairment who underwent elective total knee arthroplasty experienced higher rates of postoperative delirium and postoperative functional dependence compared with matched patients without cognitive impairment, according to a retrospective database study.
Researchers analyzed data from the American College of Surgeons National Surgical Quality Improvement Program Geriatric Surgery Pilot Program collected from 2014 to 2018. The analysis included 6,350 patients aged 65 years or older undergoing elective total knee arthroplasty, including 126 patients with documented preoperative cognitive impairment. After propensity score matching, 104 patients with cognitive impairment were compared with 104 patients without cognitive impairment.
The primary outcome was 30-day mortality. Secondary outcomes included postoperative delirium, complications, hospital length of stay, postoperative functional status, and discharge location.
Postoperative delirium occurred in 27% of patients with cognitive impairment compared with less than 1% of patients without cognitive impairment (OR 40.15; 95% CI, 5.3–304.13), though the wide confidence interval reflects the relatively small matched cohort.
In addition to higher delirium rates, patients with cognitive impairment experienced markedly worse postoperative functional status. Although 98% of patients in both matched groups were independent in activities of daily living at baseline, only 17% of patients with cognitive impairment remained independent postoperatively compared with 48% of patients without cognitive impairment. Overall, 83% of patients with cognitive impairment were partially or totally dependent following surgery vs 52% of patients without cognitive impairment.
Nonhome discharge occurred in 50% of patients with cognitive impairment compared with 36% of patients without cognitive impairment. The association reached conventional statistical significance (p = 0.029) but did not meet the Bonferroni-adjusted threshold applied across all outcomes comparisons.
Thirty-day mortality was 0% in both matched groups. Rates of complications, including infection, pneumonia, transfusion, reintubation, and sepsis, were low overall, although several complications occurred numerically more often among patients with cognitive impairment.
Researchers noted that spinal anesthesia was more common than general anesthesia in both matched cohorts and was used more frequently among patients with cognitive impairment (83% vs 73%). However, the study lacked sufficient sample size to assess the effect of anesthesia type on delirium risk.
The authors also highlighted that only about 2% of patients in the overall cohort had documented cognitive impairment, despite prior literature suggesting that approximately 20% of older elective surgical patients may have unrecognized baseline cognitive impairment. Because cognitive impairment was identified through clinical documentation rather than standardized cognitive testing, the true prevalence was likely underestimated.
The study was limited by its retrospective observational design and reliance on database documentation. Postoperative delirium was identified through chart audit terms suggestive of an acute confused state rather than standardized delirium assessments, which may have resulted in underreporting. The database also lacked standardized information regarding postoperative rehabilitation and physical therapy exposure.
The researchers noted that nonhome discharge across the broader surgical population contributes an estimated $1.82 billion annually in postoperative rehabilitation costs, underscoring the potential health system implications of identifying high-risk patients preoperatively.
“Early identification of patients with CI and preemptive interventions such as multidisciplinary care involving geriatricians and/or neurocognitive specialists may decrease adverse outcomes for these high-risk patients,” wrote lead study author Sindhu Krishnan, MD, of Brigham and Women’s Hospital/Harvard Medical School, and colleagues.
The investigators also highlighted potential preventive strategies discussed in prior literature, including preoperative Mini-Cog screening, geriatric co-management, and multimodal prehabilitation programs aimed at reducing postoperative complications and preserving functional recovery.
Disclosures: Study coauthor Richard D. Urman, MD, reported receiving fees or funding from Merck, Medtronic/Covidien, AcelRx, Pfizer, Acacia, and Heron. The study received no external funding.
