30-day Mortality Following Surgery for Spinal Epidural Abscess: Incidence, Risk Factors, Predictive Algorithm, and Associated Complications.

STUDY

DESIGN

Retrospective case-control study.

OBJECTIVE

To determine incidence and timing of mortality following surgery for spinal epidural abscess (SEA), identify risk factors for mortality, and identify complications associated with mortality.

SUMMARY OF BACKGROUND DATA: SEA is a serious condition with potentially devastating sequelae. There is a paucity of literature characterizing mortality following surgery for SEA.

METHODS

The National Surgical Quality Improvement Program (NSQIP) database was used. Patients with a diagnosis of SEA were included. A Cox proportional hazards model identified independent risk factors for 30-day mortality. A predictive model for mortality was created. Multivariate models identified postoperative complications associated with mortality.

RESULTS

There were 1094 patients included, with 40 cases of mortality (3.7%), the majority of which occurred within 2 weeks postoperatively (70%). Independent risk factors for 30-day mortality were age>60 years (hazard ratio [HR]: 2.147, P = 0.027), diabetes (HR: 2.242, P = 0.015), respiratory comorbidities (HR: 2.416, P = 0.037), renal comorbidities (HR: 2.556, P = 0.022), disseminated cancer (HR: 5.219, P = 0.001), and preoperative thrombocytopenia (HR: 3.276, P = 0.001). A predictive algorithm predicts a 0.3% mortality for zero risk factors up to 37.5% for 4 or more risk factors. A ROC area under curve (AUC) was 0.761, signifying a fair predictor (95% CI: 0.683-0.839, P < 0.001). Cardiac arrest (adjusted odds ratio [aOR]: 72.240, 95% confidence interval [CI]: 27.8-187.721, P < 0.001), septic shock (aOR: 15.382, 95% CI: 7.604-31.115, P < 0.001), and pneumonia (aOR: 2.84, 95% CI: 1.109-7.275, P = 0.03) were independently associated with mortality.

CONCLUSION

The 30-day mortality rate following surgery for SEA was 3.7%. Of the mortalities that occurred within 30 days of surgery, the majority occurred within 2 weeks. Independent risk factors for mortality included older age, diabetes, hypertension, respiratory comorbidities, renal comorbidities, metastatic cancer, and thrombocytopenia. Risk for mortality ranged from 0.3% to 37.5% based on number of risk factors. Septic shock, cardiac arrest, and pneumonia were associated with mortality.

LEVEL OF EVIDENCE: 3.