Incidence and risk factors of postoperative delirium following total knee arthroplasty: A retrospective Nationwide Inpatient Sample database study.

BACKGROUND

Postoperative delirium is a common complication following major surgeries, causing a variety of adverse effects. However, the incidence and risk factors of delirium after primary total knee arthroplasty (TKA) has not been well studied using a large-scale national database.

METHODS

A retrospective database analysis was performed based on Nationwide Inpatient Sample (NIS) from 2005-2014. Patients who underwent primary TKA were included. Patient demographics, comorbidities, length of stay (LOS), total charges, type of payer, in-hospital mortality, and perioperative complications were evaluated.

RESULTS

A total of 1,228,879 TKAs were obtained from the NIS database. The general incidence of delirium after TKA was 1.00%, which peaked in the year 2008.Patients with delirium after TKA presented increased comorbidities, LOS, hospital charges, usage of medicare, and in-hospital mortality (P < 0.0001). Delirium following TKA was associated with medical complications during hospitalization including acute renal failure, acute myocardial infarction, pneumonia, pulmonary embolism, stroke, and urinary tract infection. Risk factors of postoperative delirium included advanced age, neurological disorders, alcohol and drug abuse, depression, psychoses, fluid and electrolyte disorders, diabetes, weight loss, deficiency and chronic blood loss anemia, coagulopathy, congestive heart failure, chronic pulmonary disease, pulmonary circulation disorders, peripheral vascular disorders, chronic renal failure, and teaching hospital. Notably, neurological disorders were found to have the strongest association with the occurrence of postoperative delirium.

CONCLUSION

A relatively low incidence of delirium after TKA was identified. It is of benefit to study risk factors of postoperative delirium to ensure the appropriate management and moderate its consequences.