Neutrophil-to-lymphocyte ratio is associated with 30-day mortality in acute pulmonary embolism across European Society of Cardiology risk categories.

BACKGROUND: Pulmonary embolism (PE) remains a major cause of cardiovascular morbidity and mortality. The neutrophil-to-lymphocyte ratio (NLR) is a readily available biomarker reflecting inflammatory stress responses and has been proposed as a predictor of cardiovascular outcomes. OBJECTIVES: This study evaluated the association between elevated NLR and 30-day all-cause mortality in patients with acute PE across European Society of Cardiology (ESC) risk categories. METHODS: A retrospective cohort study of adults with acute PE diagnosed by computed tomography pulmonary angiography was conducted within an integrated health system from January 2019 to January 2025. NLR was calculated from admission complete blood counts and categorized as elevated using a prespecified cutoff (≥7). Patients were stratified by ESC risk category. Multivariable logistic regression was used to assess association between elevated NLR and 30-day mortality, adjusting for age, sex, cancer status, and congestive heart failure. RESULTS: Among 1525 patients with acute PE, 46.4% were ESC low risk, 51.7% intermediate risk, and 1.9% high risk; 30-day all-cause mortality occurred in 6.6% of patients and was markedly higher among patients with elevated NLR in the ESC low-risk (10.4% vs 1.2%) and intermediate-risk (16.2% vs 3.6%) groups. Elevated NLR was independently associated with increased mortality in ESC low-risk (odds ratio, 5.68; 95% CI, 2.09-15.44) and intermediate-risk patients (odds ratio, 4.60; 95% CI, 2.57-8.24). Addition of NLR to the ESC-based model improved discrimination for 30-day mortality (C-statistic, 0.812-0.853; P = .003). CONCLUSION: Elevated NLR is independently associated with increased 30-day all-cause mortality in patients with acute pulmonary embolism classified as ESC low or intermediate risk. Consequently, NLR may serve as a simple adjunctive marker for refining PE risk stratification; however, prospective validation is needed.