The prognostic utility of neutrophil–lymphocyte ratio in spinal surgery: A systematic review and meta-analysis

•A high baseline NLR is linked with reduced overall survival in spinal tumour.•A high baseline NLR is linked with poor functional recovery in spinal cord injury.•High postop (day 3 – 7) NLR levels are linked with greater risks of complications.•Baseline and day 1–2 postop NLR levels do not predict the risks of complications. Neutrophil-lymphocyte ratio (NLR) is reportedly an effective prognostic tool across various medical and surgical fields, but its value in spinal surgery is unestablished. We aim to investigate the relationship between elevated baseline/postoperative NLR and patient outcomes in spinal surgery. We performed a systematic search in PubMed, EMBASE, and SCOPUS databases for studies investigating the prognostic value of NLR in spine patients.Odds ratios (ORs) and hazard ratios (HRs) with 95% confidence intervals (CIs) were analysed on the RevMan 5.4 software. Where meta-analysis was not possible, we vote-counted the direction of the effect of elevated NLR. The GRADE framework for prognostic factor research was utilised to assess the certainty of the evidence for each outcome measure. Five outcome measures (overall survival, mortality, disease-free survival, functional recovery and complications) were assessed across 16 studies involving 5471 patients. Elevated baseline NLR was associated with reduced overall survival (HR: 1.63, 95 % CI: 1.05 – 2.54) (GRADE: low) and worsened functional recovery (OR: 0.93, 95 % CI: 0.87 – 0.98) (GRADE: low). There was no association between baseline NLR and disease-free survival (HR: 2.42, 95 % CI: 0.49 – 11.83) (GRADE: very low) or mortality (OR: 1.39, 95 % CI: 0.41 – 4.75) (GRADE: very low). Elevated NLR levels measured on days 3–4 and days 6–7 postoperatively, but not NLR measured at baseline or on days 1–2 postoperatively, were associated with greater risks of complications (GRADE: low). NLR is an objective tool with the potential to identify the patients that would benefit from surgery and facilitate shared decision-making.