• Hiroyuki Inose, Yutaka Kobayashi, Masato Yuasa, Takashi Hirai, Toshitaka Yoshii, and Atsushi Okawa.
• Department of Orthopaedic Surgery, Graduate School, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo, Japan.
• Spine. 2019 Dec 1; 44 (23): E1356-E1361.

Study DesignThis was a retrospective observational study.ObjectiveTo assess the diagnostic value of procalcitonin (PCT) and neutrophil lymphocyte ratio (NLR) for predicting surgical site infection (SSI) in patients undergoing spinal instrumentation surgery, we analyzed a large consecutive cohort of patients who had undergone spinal instrumentation surgery.Summary Of Background DataAlthough PCT and NLR are commonly used as markers for bacterial infection, the diagnostic value of these factors for predicting SSI in the context of spinal instrumentation surgery has not been extensively investigated.MethodsWe retrospectively investigated 242 patients who underwent spinal instrumentation surgery and evaluated the significance of various postoperative measures for predicting SSI, including PCT and NLR. We then determined the diagnostic cut-off values for these markers in the prediction of SSI using receiver operating characteristic curve analysis.ResultsAmong the 242 patients analyzed, 10 were diagnosed with infection. Even though univariate analysis showed that neutrophil percentage and NLR at 6 to 7 days postoperatively were significant predictors for SSI, PCT at 6 to 7 days postoperatively did not differ significantly between the SSI and non-SSI groups. The cut-off value used for neutrophil percentage at 6 to 7 days postoperatively was more than 69.0% [sensitivity, 80.0%; specificity, 70.0%; area under the curve, 0.737]. The cut-off value used for NLR at 6 to 7 days postoperatively was 3.87 (sensitivity, 70.0%; specificity, 73.2%; area under the curve, 0.688).ConclusionNeutrophil percentage and NLR at 6 to 7 days postoperatively were more useful markers than PCT at 6 to 7 days postoperatively for early prediction of SSI in patients who had undergone spinal instrumentation surgery. Therefore, routine use of PCT as a predictor of postoperative infection is not supported by the results of this study.Level Of Evidence4.

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