Value of platelet/lymphocyte ratio as a predictor of all-cause mortality after non-ST-elevation myocardial infarction

Abstract

Prior studies demonstrated the association between the major adverse cardiovascular outcomes and both higher platelet and lower lymphocyte counts. Our study explores the value of the platelet/lymphocyte ratio (PLR) as a marker of long-term mortality in patients presented with non-ST segment elevation myocardial infarction (NSTEMI). This is an observational study with a total 619 NSTEMI patients admitted to a tertiary center between 2004 and 2006. Patients were stratified into equal tertiles according to their admission PLR. The primary outcome, 4 year all-cause mortality, was compared among the PLR tertiles. The first, second and third PLR tertiles were PLR < 118.4, 118.4 ≤ PLR ≤ 176, and PLR > 176, respectively) included 206, 206 and 207 patients, respectively. There was a significant higher 4 year all-cause mortality in the higher PLR tertiles (the mortalities were 17, 23 and 42 % for the first, second and third PLR tertiles respectively, p < 0.0001). After exclusion of patients expired in the first 30 days, patients in the first PLR tertile had a significant lower 4 year mortality (33/205, 16 %) versus those in the third PLR tertile (72/192, 38 %), p < 0.0001. After controlling for Global Registry of Acute Coronary Events risk scores and other confounders, the hazard ratio of mortality increased 2 % per each 10 U increase of PLR (95 % CI 1.01-1.03, p < 0.0001). In patients with PLR ≥ 176, the mortality rate was statistically higher in those received mono-antiplatelet (30/60 = 50 %) compared to those received dual antiplatelet therapy (48/149 = 32 %), p = 0.0018. However in PLR < 176, the mortality was not significantly different between mono-antiplatelet group (20/94 = 21 %) versus dual antiplatelets group (53/213 = 25 %), p = 0.56. The PLR is a significant independent predictor of long-term mortality after NSTEMI. Among patients with PLR > 176, patients with dual antiplatelet therapy had lower mortality versus those with mono-platelet therapy. Further studies are needed to clarify these findings.