Diagnostic performance of neutrophil-to-lymphocyte ratio in periprosthetic joint infection: A systematic review and meta-analysis.

Objectives: Periprosthetic joint infection (PJI) is one of the most severe complications following joint replacement surgery, leading to significant morbidity, mortality, and healthcare burden. The neutrophil-to-lymphocyte ratio (NLR) has emerged as a potential biomarker for diagnosing PJI due to its simplicity and cost-effectiveness. However, the diagnostic utility of NLR remains unclear, warranting a systematic review and meta-analysis. Materials and Methods: This study systematically reviewed 23 studies involving 11,657 patients, of whom 2061 had PJI. The pooled sensitivity, specificity, diagnostic odds ratio, and area under the summary receiver operating characteristic curve (AUC) were calculated to evaluate the diagnostic performance of NLR. Subgroup analyses were conducted based on the type of arthroplasty (total knee or hip replacement) and PJI classification (acute or chronic). Publication bias was assessed using Deeks' funnel plot. Results: The pooled sensitivity and specificity of NLR for diagnosing PJI were 0.71 (95% confidence interval [CI]: 0.66-0.76) and 0.70 (95% CI: 0.65-0.75), respectively. The AUC was 0.76, demonstrating moderate diagnostic accuracy. Subgroup analyses revealed consistent findings across acute and chronic PJI cases, as well as total knee and hip arthroplasties. NLR cutoff values ranged from 2.1 to 3.82 across studies, reflecting a lack of standardization. Conclusion: NLR is a promising biomarker for diagnosing PJI, offering moderate diagnostic accuracy and practical advantages due to its accessibility and cost-effectiveness. However, standardization of NLR thresholds and further validation in prospective studies are needed to optimize its clinical utility.