Risk Factors for 30- and 90-Day Readmissions Due To Surgical Site Infection Following Posterior Lumbar Fusion

STUDY DESIGN: This was a retrospective cohort study. OBJECTIVE: Identify the independent risk factors for 30- and 90-day readmission because of surgical site infection (SSI) in patients undergoing elective posterior lumbar fusion (PLF). SUMMARY OF BACKGROUND DATA: SSI is a significant cause of morbidity in the 30- and 90-day windows after hospital discharge. There remains a gap in the literature on independent risk factors for readmission because of SSI after PLF procedures. In addition, readmission for SSI after spine surgery beyond the 30-day postoperative period has not been well studied. METHODS: A retrospective analysis was performed on data from the 2012 to 2014 Healthcare Cost and Utilization Project Nationwide Readmissions Database. The authors identified 65,121 patients who underwent PLF. There were 191 patients (0.30%) readmitted with a diagnosis of SSI in the 30-day readmission window, and 283 (0.43%) patients readmitted with a diagnosis of SSI in the 90-day window. Baseline patient demographics and medical comorbidities were assessed. Bivariate and multivariate analyses were performed to examine the independent risk factors for readmission because of SSI. RESULTS: In the 30-day window after discharge, this study identified patients with liver disease, uncomplicated diabetes, deficiency anemia, depression, psychosis, renal failure, obesity, and Medicaid or Medicare insurance as higher risk patients for unplanned readmission with a diagnosis of SSI. The study identified the same risk factors in the 90-day window with the addition of diabetes with chronic complications, chronic pulmonary disease, and pulmonary circulation disease. CONCLUSIONS: Independent risk factors for readmission because of SSI included liver disease, uncomplicated diabetes, obesity, and Medicaid insurance status. These findings suggest that additional intervention in the perioperative workup for patients with these risk factors may be necessary to lower unplanned readmission because of SSI after PLF surgery.