Surgical site infection in spinal metastasis: risk factors and countermeasures.

STUDY DESIGN A retrospective review (phase 1) and prospective clinical study (phase 2). OBJECTIVES To identify independent risk factors for surgical site infection (SSI) and to evaluate the positive effect of prostaglandin E1 (PGE1) to decrease the risk of SSI in patients with spinal metastasis. SUMMARY OF BACKGROUND DATA Surgery for spinal metastasis is associated with an increased risk of SSI. Although previous reports have evaluated risk factors of SSI for spinal metastasis, most of the studies lack multivariate analysis. A recent study demonstrated the utility of PGE1 in decreasing wound complications in patients with prior irradiation. The role of PGE1 in surgery for spinal metastasis has not been previously evaluated. METHODS One hundred ten patients with spinal metastasis were retrospectively reviewed (phase 1). Risk factors for SSI were analyzed using logistic regression. Phase 2 was a prospective clinical trial investigating the utility of PGE1 at reducing the rate of SSI. Ninety-four patients with spinal metastasis were treated at our institute. The infection rate and risk factors identified in phase 1 and 2 were compared. RESULTS The rate of SSI during phase 1 was 7.1%. Independent risk factors identified by multivariate logistic regression were diabetes, and preoperative irradiation. The rate of SSI for patients who had irradiation before surgery was 32%, whereas the rate for patients without irradiation was 1.1%. This difference was statistically significant. The rate of SSI in phase 2 was 3.1%. In phase 2 patients who received preoperative irradiation, the rate of SSI was 4.5%. The difference between phase 1 and phase 2 was statistically significant. CONCLUSION This study identified diabetes and preoperative irradiation to be independent risk factors for SSI in patients with spinal metastasis. PGE1 administration was found to significantly decrease the incidence of SSI in patients with spinal metastasis who underwent preoperative irradiation.