Incidence and Risk Factors of Postoperative Delirium Following Primary Elective Total Hip Arthroplasty: A Retrospective Nationwide Inpatient Sample Database Study

Background: Postoperative delirium is a common complication following major surgeries, leading to a variety of adverse effects. However, there is a paucity of literatures studying the incidence and risk factors of delirium after primary elective total hip arthroplasty (THA) using a large-scale national database. Methods: A retrospective database analysis was performed based on Nationwide Inpatient Sample (NIS) from 2009-2014. Patients who underwent primary elective THA were included. Patient demographics, comorbidities, length of hospital stay (LOS), total charges, in-hospital mortality, and major and minor perioperative complications were evaluated. Results: A total of 388,424 primary elective THAs were obtained from the NIS database, and the general incidence of delirium after THA was 0.90%. Patients with delirium after THA presented more comorbidities, increased LOS, extra hospital charges, and higher in-hospital mortality rate (P<0.001). Delirium following THA was associated with major complications during hospitalization including acute renal failure and pneumonia. Risk factors of postoperative delirium included advanced age, alcohol or drug abuse, depression, neurological disorders, psychoses, fluid and electrolyte disorders, diabetes, weight loss, deficiency anemia, coagulopathy, hypertension, congestive heart failure, valvular disease, pulmonary circulation disorders, peripheral vascular disorders, and renal failure. Both female and obesity were detected to be protective factors. Conclusions: The results of our study identified a relatively low incidence of delirium after primary elective THA. Postoperative delirium of THA was associated with increased comorbidities, LOS, total charges, in-hospital mortality, and major perioperative complications including acute renal failure and pneumonia. It is of benefit to study risk factors of postoperative delirium to moderate its consequences.