The neutrophil-to-lymphocyte ratio (NLR) levels predicting the surgical site infection in spinal surgery: a systematic review.

Background: Surgical site infection (SSI) is a prevalent complication in spinal surgery, associated with significant morbidity, prolonged hospital stays, and increased healthcare costs. The early detection of SSI can lead to timely intervention. Among available diagnostic methods, the neutrophil-to-lymphocyte ratio (NLR) has emerged as a simple, accessible marker with potential predictive value for SSIs. This systematic review aims to evaluate the diagnostic role of NLR, in the early detection of SSIs following spinal surgery. Methods: Following PRISMA guidelines, we conducted a comprehensive literature search in MEDLINE, Web of Science, Embase, and Scopus databases for studies examining the utility of NLR in predicting SSIs in all types of spinal surgery patients. Ultimately, 7 studies met the inclusion criteria; all retrospective in design, with sample sizes ranging from 77 to 384. Studies focused on NLR values measured at different postoperative days, solely or along with some integrating additional markers, including C-reactive protein (CRP) and body mass index (BMI), into predictive models. Results: Our study confirmed that NLR serves as a significant predictor of SSIs post-spinal surgery. Analyses of included studies revealed variable optimal NLR cutoff values, ranging from 3.21 to 4.91, dependent on postoperative day and surgery type. The highest predictive accuracy was observed when NLR was combined with CRP and lymphocyte percentage, enhancing early SSI detection. However, the variability in cutoff values and measurement timing across studies suggests limitations due to heterogeneity in study designs and patient populations, indicating the need for further research to establish standardized protocols. Conclusions: NLR could be of value for early SSI detection in spinal surgery, with its diagnostic accuracy potentially improved by combining it with other markers. However, variability in cutoff values and timing across studies suggests the need for further research to standardize these parameters. Establishing consistent protocols could improve SSI detection, enabling faster interventions and potentially enhancing patient outcomes in spinal surgery.