Risk factors for postoperative delirium in patients undergoing lower extremity joint arthroplasty: a retrospective population-based cohort study

Background With an ageing population, the demand for joint arthroplasties and the burden of postoperative delirium is likely to increase. Given the lack of large-scale data, we investigated associations between perioperative risk factors and postoperative delirium in arthroplasty surgery. Methods This retrospective population-based cohort study, utilized national claims data from the all-payer Premier Healthcare database containing detailed billing information from >25% nationwide hospitalizations. Patients undergoing elective total hip/knee arthroplasty surgery (2006-2016) were included. The primary outcome was postoperative delirium, while potential risk factors included age, gender, race, insurance type, and modifiable exposures including anesthesia type, opioid prescription dose (low/medium/high), benzodiazepines, meperidine, non-benzodiazepine hypnotics, ketamine, corticosteroids, and gabapentinoids. Results Among 1 694 795 patients' postoperative delirium was seen in 2.6% (14 785/564 226) of hip and 2.9% (32 384/1 130 569) of knee arthroplasties. Multivariable models revealed that the utilization of long acting (OR 2.10 CI 1.82 to 2.42), combined long/short acting benzodiazepines (OR 1.74 CI 1.56 to 1.94), and gabapentinoids (OR 1.26 CI 1.16 to 1.36) was associated with increased odds of postoperative delirium. Lower odds of postoperative delirium were seen for neuraxial versus general anesthesia (OR 0.81 CI 0.70 to 0.93) and with the utilization of non-steroidal anti-inflammatory drugs (OR 0.85 CI 0.79 to 0.91) as well as cyclooxygenase-2 inhibitors (OR 0.82 CI 0.77 to 0.89). Age-stratified analysis revealed lower odds with high versus low opioid dose (OR 0.86 CI 0.76 to 0.98) in patients >65 years. Findings were consistent between hip and knee arthroplasties. Conclusions In this large national cohort, we identified various modifiable risk factors (including anesthesia type and pharmaceutical agents) for postoperative delirium, demonstrating possible prevention pathways.