Incidence and risk factors for postoperative delirium after lumbar spine surgery.

STUDY DESIGN: Retrospective database analysis.

OBJECTIVE: A population-based database was analyzed to characterize the incidence, hospital costs, mortality, and risk factors associated with postoperative delirium after lumbar decompression (LD) and lumbar fusion (LF) surgical procedures.

SUMMARY OF BACKGROUND DATA: Postoperative delirium is a common complication after surgery in the elderly that leads to increased hospitalization, cost, and other adverse outcomes. The incidence of delirium after lumbar spine surgery has not been discussed in this literature.

METHODS: Data from the Nationwide Inpatient Sample were obtained from 2002-2009. Patients undergoing LD or LF for degenerative pathologies were identified. Patient demographics, comorbidities, length of stay, discharge disposition, costs, and mortality were assessed. SPSS version 20 was used for statistical analysis using independent T tests for discrete variables and χ2 tests for categorical data. Logistic regression was performed to identify independent predictors of delirium. A P value of less than 0.001 was used to denote significance.

RESULTS: A total of 578,457 LDs and LFs were identified in the United States from 2002-2009. Of these, 292,177 were LDs and 286,280 were LFs. The overall incidence of delirium was 8.4 events per 1000 cases. Patients undergoing LF had a statistically greater incidence of delirium than patients undergoing LD (11.8 vs. 5.0 per 1000; P < 0.001). Patients experiencing delirium were significantly older and more likely to be female than nonaffected patients (P < 0.001). Patients with delirium in both cohorts demonstrated significantly greater comorbidities, length of stay, greater costs, and more frequent discharge to skilled nursing facilities (P < 0.001). The presence of delirium in LD-treated patients was associated with an increased mortality rate (6.1 vs. 0.8 per 1000; P < 0.001). Logistic regression demonstrated that independent predictors of delirium included older age (≥65 yr), alcohol/drug abuse, depression, psychotic disorders, neurological disorders, deficiency anemia, fluid/electrolyte disorders, and weight loss.

CONCLUSION: The results of our study demonstrated an overall incidence of 8.4 events per 1000 lumbar spine surgical procedures. Overall analysis demonstrated an increased incidence of delirium in older females with greater comorbid conditions. Delirium was found to be associated with increased length of stay, costs, and mortality in all patients undergoing lumbar spine surgery. We recommend that physicians put greater effort into recognizing risk factors of delirium and diagnosing it in a timely manner to mitigate its effects.

LEVEL OF EVIDENCE: 3.