Correlation between neutrophil-to-lymphocyte ratio and postoperative mortality in elderly patients with hip fracture: a meta-analysis

INTRODUCTION: The neutrophil-to-lymphocyte ratio (NLR) is a crucial prognosis predictor following several major operations. However, the association between NLR and the outcome after hip fracture surgery is unclear. In this meta-analysis, we investigated the correlation between NLR and postoperative mortality in geriatric patients following hip surgery. METHOD: PubMed, Embase, Cochrane library, and Google Scholar were searched for studies up to June 2021 reporting the correlation between NLR and postoperative mortality in elderly patients undergoing surgery for hip fracture. Data from studies reporting the mean of NLR and its 95% confidence interval (CI) were pooled. Both long-term (≥ 1 year) and short-term (≤ 30 days) mortality rates were included for analysis. RESULT: Eight retrospective studies comprising a total of 1563 patients were included. Both preoperative and postoperative NLRs (mean difference [MD]: 2.75, 95% CI: 0.23–5.27; P = 0.03 and MD: 2.36, 95% CI: 0.51–4.21; P = 0.01, respectively) were significantly higher in the long-term mortality group than in the long-term survival group. However, no significant differences in NLR were noted between the short-term mortality and survival groups (MD: − 1.02, 95% CI: − 3.98 to 1.93; P = 0.5). CONCLUSION: Higher preoperative and postoperative NLRs were correlated with a higher risk of long-term mortality following surgery for hip fracture in the geriatric population, suggesting the prognostic value of NLR for long-term survival. Further studies with well-controlled confounders are warranted to clarify the predictive value of NLR in clinical practice in geriatric patients with hip fracture. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13018-021-02831-6.