Predictive value of neutrophil-lymphocyte ratio for all-cause mortality in patients with chronic obstructive pulmonary disease: a systematic review and meta-analysis.

Abstract

Background: Chronic obstructive pulmonary disease (COPD) involves inflammation as a key factor influencing its pathology and progression. This meta-analysis sought to assess the prognostic importance of the neutrophil-to-lymphocyte ratio (NLR) in individuals diagnosed with COPD.

Methods: Comprehensive searches were carried out in PubMed, Embase, Web of Science, and the Cochrane Library up to March 2025. All-cause mortality-related data were collected and analyzed. Outcomes were evaluated using odds ratios (ORs) and 95% confidence intervals (CIs).

Results: Following a thorough review of the literature and a rigorous screening process, a total of 24 studies including 18,597 patients were selected for this meta-analysis. The cut-off range of NLR in all included literatures was 1.3 to 16.83. Analysis of categorical variables showed that COPD patients with elevated NLR levels faced a significantly higher all-cause mortality risk compared to those with lower NLR levels (OR: 1.03, 95% CI: 1.01-1.06, P = 0.009, I² = 89%). For continuous variables, deceased COPD patients exhibited significantly elevated NLR levels compared to survivors (SMD: 1.23, 95% CI: 0.90-1.57, P < 0.00001, I² = 97%). The subgroup analysis highlighted study design and the timing of NLR measurement as potential contributors to heterogeneity. Subgroup analysis showed that NLR had a better predictive value for disease in AECOPD subgroups.

Conclusion: This meta-analysis demonstrates a correlation between increased NLR levels and heightened all-cause mortality risk in COPD patients. Nevertheless, given the inherent limitations of this study, additional multi-center, prospective clinical trials are essential to confirm these findings.