Anesthetic technique and incidence of delirium after total knee or hip arthroplasty: a nationwide cohort study

Background The optimal type of anesthesia for reducing postoperative delirium remains undetermined. This study aimed to assess the relationship between type of anesthesia and postoperative delirium. Methods This retrospective national cohort study used data collected between 2016 and 2021 from the National Health Insurance Service of South Korea. Adult patients who underwent primary total hip or total knee arthroplasty under general or regional anesthesia were included. Patients with postoperative delirium were identified after arthroplasty according to the International Classification of Diseases 10th revision code for delirium (F05). The patients were divided into two groups: regional anesthesia (RA group) and general anesthesia (GA group). The primary endpoint was the incidence of postoperative delirium during hospitalization after total hip or knee arthroplasty. Results Our study sample consisted of 664,598 patients: 474,932 in the RA group and 189,666 in the GA group. After propensity score (PS) matching, 276,582 patients (138,291 in each group) were included in the final analysis. In the PS-matched cohort, the incidence of delirium following total knee or total hip arthroplasty was 2.8% (3,842/138,291) in the GA group and 2.3% (3,147/138,291) in the RA group. In logistic regression, the RA group was associated with 18% (odds ratio: 0.82, 95% confidence interval: 0.78, 0.86; P < 0.001) lower postoperative incidence than the GA group. Conclusion Compared to general anesthesia, regional anesthesia was associated with a decreased incidence of postoperative delirium in patients who underwent total hip or total knee arthroplasty. Our findings indicate that avoiding general anesthesia may prevent delirium after lower limb surgery.