Platelet-to-lymphocyte ratio as a novel marker of in-hospital and long-term adverse outcomes among patients with acute pulmonary embolism: A single center large-scale study

Background: The interaction of platelets with leukocytes is a well-known process both in progression and prognosis of acute pulmonary embolism (PE). Recently, platelet to lymphocyte ratio (PLR) is emerged as an indirect inflammatory indicator which was shown to be associated with adverse cardiovascular events in various clinical conditions, including acute PE. However, the long-termprognostic value of PLR in acute PE has not been investigated thoroughly. Therefore, we aimed to assess the impact of PLR on both in-hospital and long-term adverse outcomes in acute PE. Methods: A total of 459 patients with definite diagnosis of acute PE between January 2009 and January 2016 were enrolled. On admission, blood sampling to calculate PLR and detailed clinical data were obtained. Patients were divided into tertiles according to the admission PLR levels. Simplified PE severity index (sPESI) score and computerized tomography (CT) based pulmonary artery obstruction index were calculated for each patient. Results: Mean sPESI score of the study population was 1.6. A total of 34 patients (7.4%) died during index hospitalization. At median 28.8 months follow-up, all-cause mortality was observed in 81 patients (1.9%). Patients in the highest tertile of PLR revealed a higher rate of in-hospital adverse events including cardiogenic shock, the necessity for thrombolytic therapy and in-hospital mortality as well as long-term all-cause mortality. In multivariate analysis, the PLR was found to be a significant predictor of both in-hospital adverse events (OR: 1.588, 95% CI: 1.116-2.154, p = 0.004) and long-term all-cause mortality (OR: 1.746, 95% CI: 1.211-2.865, p = 0.001). Conclusions: The PLR, as a simple, inexpensive and available marker of inflammatory and prothrombotic status, seemed to be a novel predictor of in-hospital and long-term adverse outcomes in patients with acute PE. (C) 2016 Elsevier Ltd. All rights reserved.