Inflammation-Based Risk Assessment in Acute Pulmonary Embolism: Diagnostic and Prognostic Implications of the Neutrophil-to-Lymphocyte Ratio

Objectives: Acute pulmonary embolism (PE) is a serious cardiovascular disorder that may lead to substantial morbid-ity and mortality if not recognized early. Timely diagnosis and accurate assessment of disease severity are essential for appropriate treatment planning. Although imaging techniques and cardiac biomarkers are commonly used in the diag-nostic process, there remains a need for practical laboratory markers that are inexpensive, rapidly obtainable, and easily applicable in routine clinical settings. The neutrophil-to-lymphocyte ratio (NLR), derived from peripheral blood counts, has recently gained attention as an indicator of inflammatory activation. In this study, we investigated the diagnostic significance of NLR in acute PE and examined its association with clinical severity and mortality outcomes.
Methods: A total of 100 patients diagnosed with acute PE by computed tomography pulmonary angiography and 94 healthy individuals were retrospectively evaluated. Patients were categorized according to the 2014 European Society of Cardiology risk stratification model into low/intermediate-low-risk and intermediate-high/high-risk groups. Laboratory data obtained within the first 6 hours after hospital admission were analyzed. Receiver operating characteristic (ROC) curve analysis was used to determine the diagnostic performance of NLR.
Results: Patients with acute PE had significantly higher NLR values compared with healthy controls (5.7±4.3 vs. 2.08±1.6, p<0.001). ROC analysis demonstrated that NLR had favorable diagnostic performance for acute PE, with an area under the curve of 0.855. An NLR threshold above 2.56 provided 76% sensitivity and 84.6% specificity. Moreover, NLR levels were significantly greater in intermediate-high/high-risk patients compared with low/intermediate-low-risk patients (6.82±5.1 vs. 4.93±3.3, p=0.031). Although higher NLR values were observed among patients who died during follow-up, no statistically significant relationship was identified between NLR and short- or long-term mortality. Conclusion: The present findings suggest that NLR may be a useful supportive biomarker in the early evaluation of acute PE. Elevated NLR levels were associated with increased disease severity. Although its prognostic value for mortal-ity was not clearly demonstrated, NLR may still contribute to clinical risk assessment because of its rapid availability and ease of calculation.

Keywords: Inflammation, pulmonary embolism, mortality, neutrophil-to-lymphocyte ratio, risk stratification