Platelet-to-lymphocyte ratio is a predictor of long-term mortality in patients with acute coronary syndrome

Introduction
Atherosclerosis is a chronic inflammatory process and inflammation is an important component of acute coronary syndrome (ACS). Platelet-to-lymphocyte ratio (PLR) is a useful parameter showing the degree of the inflammatory response.

Aim
To explore the association between PLR and long-term mortality in patients with ACS.

Material and methods
A total of 538 patients who had a diagnosis of ACS between January 2012 and August 2013 were followed up to 60 months. On admission, blood sampling to calculate PLR and detailed clinical data were obtained.

Results
In total, 538 patients with a mean age of 61.5 ±13.1 years (69% male) were enrolled in the study. Median follow-up was 79 months (IQR: 74–83 months). Patients were divided into 3 tertiles based on PLR levels. Five-year mortality of the patients was significantly higher among patients in the upper PLR tertile when compared with the lower and middle PLR tertile groups (55 (30.7%) vs. 27 (15.0%) and 34 (19.0%); p < 0.001, p = 0.010 respectively). In the Cox regression analysis, a high level of PLR was an independent predictor of 5-year mortality (OR = 1.005, 95% CI: 1.001–1.008, p = 0.004). Kaplan-Meier analysis according to the long-term mortality-free survival revealed the higher occurrence of mortality in the third PLR tertile group compared to the first (p < 0.001) and second tertiles (p = 0.009).

Conclusions
PLR, which is an easily calculated and universally available marker, may be useful in long-term risk classification of patients presenting with ACS.