Usefulness of Lymphocyte ratio and CRP Level for Early Detection of Surgical Site Infection Following spinal surgery

Abstract Background: To investigate the significant laboratory markers for early diagnosis of surgical site infection after spinal surgery. And determine the diagnostic cut-off values of these markers Methods: A total of 67 patients participated in the study: 11 patients who developed surgical site infection after spinal surgery (SSI Group) and 56 patients were compared with the infected group in terms of age，gender, operating time and intraoperative blood loss (Non-SSI Group). The white blood cell (WBC) count , WBC differential , C-reactive protein (CRP) and erythrocyte sedimentation rate(ESR) were determined before and 1, 3 and 7 days postoperatively . Then, we determine the diagnostic cutoff for these markers by using the receiver operating characteristic curve. Results: The CRP, ESR and WBC were significantly higher in the SSI group at 3 and 7 days postoperatively. The lymphocyte ratio at 3 days postoperatively was significantly lower in the SSI Group. Using the receiver operating characteristic curve，lymphocyte ratio <11.5% at 3 days postoperatively (sensitivity 90.9%, specificity 75.4%, area under the curve [AUC] 0.919), and C-reactive protein level >26 mg/dL at 7 days postoperatively (sensitivity 90.9%, specificity 87.7%, area under the curve [AUC] 0.954) were the significant laboratory marker for early detection of SSI Conclusion: Lymphocyte ratio<11.5% at 3 days and C-reactive protein levels>26.5mg/dl at 7 days after spinal surgery are reliable markers of SSI.