Preoperative Hemoglobin Level Is Associated with Wound Infection After Oncologic Surgery for Osseous Spine Metastases Independent of Blood Loss or Transfusion

Introduction: Wound infection in oncological surgery for metastatic spinal tumors is a complication that adds considerable morbidity to patients. The rate of surgical site infection (SSI) is higher than for other spine procedures and oftentimes results in need for long-term antibiotic treatment and revision surgery. In surgical patients, anemia and blood loss can contribute to inadequate tissue perfusion and oxygenation during the healing process. The purpose of this study was to investigate the association between preoperative hemoglobin, blood loss, and transfusion with postoperative SSI in spinal tumor surgery.

Methods: Our institutional spinal oncology database identified 155 consecutive patients operated on between April 2012 and April 2022 for cord compression and/or mechanical instability. Inclusion criteria were patients with a minimum follow-up of 30 days; based on this, 13 patients were excluded. Our primary endpoint was SSI confirmed by positive cultures. The main independent variables that we examined were preoperative hemoglobin level, blood loss, and transfusion. Multivariate regression analyses were performed that also controlled for other potential confounders.

Results: A total of 142 patients met inclusion criteria with an SSI rate of 6% (8 of 142). Six patients were infected with gram-negative bacteria and two with gram-positive bacteria. The wound revision/washout rate was 63% (5 of 8). After controlling for intraoperative blood loss and perioperative transfusion, preoperative hemoglobin level was the only significant factor associated with SSI (odds ratio 0.64 [95% confidence interval 0.42 to 0.99]; p = 0.046). Factors not associated with SSI included age, history of spine radiation, body mass index, diabetes, smoking, or operative time, among others.

Conclusion : Higher preoperative hemoglobin levels were associated with less likelihood of postoperative SSI after metastatic spinal tumor surgery in this study, independent of intraoperative blood loss or transfusion. Inadequate tissue oxygenation is likely a contributing factor for infection development. Future research into perioperative optimization is needed.