Predictive value of lymphocyte ratio and CRP level for early detection of surgical site infection following lumbar spinal surgery

Abstract Objective To investigate the predictive value of laboratory predictors, such as C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), white blood cell (WBC) count, and WBC differential count, for the early diagnosis of surgical site infection (SSI) after lumbar spinal surgery. We also sought to determine the diagnostic thresholds for these markers. Methods A total of 112 patients participated in the study: 11 patients who developed SSI after lumbar spinal surgery (SSI group) and 91 non-SSI patients as controls (non-SSI group). White blood cell (WBC) count, WBC differential count, CRP level, and ESR were determined 1 day before surgery and on postoperative day (POD) 1, POD3, and POD7. The diagnostic thresholds for these markers were determined with the receiver operating characteristic curve. Results CRP, ESR, and WBC were significantly higher in the SSI group than in the non-SSI group on POD3 and POD7 ( P < 0.05). The lymphocyte ratio was significantly lower in the SSI group, compared with the non-SSI group, on POD3 ( P < 0.05). Analysis of the receiver operating characteristic curve revealed that lymphocyte ratio < 11.5% on POD3 (sensitivity 90.9%, specificity 75.4%, area under the curve [AUC] 0.919), and C-reactive protein level > 26 mg/dL on POD7 (sensitivity 90.9%, specificity 87.7%, area under the curve [AUC] 0.954) were significant laboratory predictors for the early detection of SSI. Conclusion Lymphocyte ratio < 11.5% on POD3 and CRP levels > 26.5 mg/dL on POD7 are reliable predictors for SSI after lumbar spinal surgery.