289 Neutrophil to Lymphocyte Ratio and Platelet to Lymphocyte Ratio as Predictive Markers for Pulmonary Embolism

Abstract

Acute pulmonary embolism (APE) is a potentially life threatening condition and a leading cause of mortality worldwide. Due to the urgency of establishing a diagnosis which can alter life-saving management, the concern for APE leads to excessive imaging with CT pulmonary angiography particularly in the emergency department. Neutrophil-to-Lymphocyte ratio (NLR) and Platelet-to-Lymphocyte ratio (PLR) have recently been evaluated as predictive markers for deep venous thrombosis (DVT), however, few studies have explored their application for the evaluation of acute pulmonary embolism. Given that a complete blood count (CBC) is a routinely ordered, easily accessible and inexpensive evaluation of prothrombotic and inflammatory status, it is of great significance to explore the aforementioned ratios as an alternative diagnostic tool when evaluating for APE. The ultimate goal is to gain insight into alternative diagnostic markers for APE and subsequently reduce the number of unnecessary CT Angiograms performed. This study evaluated the role of the PLR and NLR in those patients with unprovoked APE, and tested the hypothesis that a “negative” NLR of ≤ 3.4 is effective to rule out APE, while a “positive” PLR of ≥ 260 is effective to rule in APE. In this retrospective analysis, 494 patient encounters from 2012 to 2019 from a community-based hospital setting with confirmed APE were evaluated, and 106 were enrolled in the study. Inclusion criteria included confirmed APE since 2012. Exclusion criteria included surgery within the last 35 days, APE due to discontinuation of anticoagulation, current pregnancy, active chemotherapy or radiation therapy, confirmed DVT during admission, sepsis, or other known hypercoagulable state. APEs were confirmed via CTA chest (98.1%) or V/Q scan (1.9%). NLR median in our study population was 3.60 (0.520, 27.9), while the PLR median was 132.1 (39.65, 578.3). There was no statistically significant association between NLR or PLR and age, sex, ethnicity, or past medical history. NLR was negative in 55.14% of participants, while PLR was positive in only 14.95% of participants. Using our outlined criteria, the NLR is inappropriate as a screening tool to rule out APE, with a specificity of 44.86%. While PLR may have use in ruling in unprovoked APE, the sensitivity is low at 14.95%. Although the NLR and PLR have been shown to be predictive for DVT in prior studies, they do not appear similarly efficacious in the evaluation of APE.View Large Image Figure ViewerDownload Hi-res image Download (PPT)