Prognostic value of platelet-to-lymphocyte ratio in acute coronary syndrome: a systematic review and meta-analysis.

BACKGROUND: The aim of this study was to investigate whether the platelet-to-lymphocyte ratio (PLR) is an independent predictor of all-cause mortality and cardiovascular events in patients with acute coronary syndrome (ACS). METHODS: PubMed, Embase, and the Cochrane Library were searched for relevant cohort studies regarding the association between PLR and outcomes of patients with ACS. Either a random- or a fixed-effect model was used for pooling data. RESULTS: Eight studies involving 6627 patients with ACS were included. The cutoff PLR value for defining risk groups was 150, and patients were assigned to the low (≤150) or high (>150) PLR groups.The pooled relative risk (RR) values of in-hospital and long-term mortality were 2.15 [95% CI (confidence interval),1.73-2.67; P < 0.00001] and 2.27 (95% CI, 1.35-3.80; P = 0.002), respectively, comparing the high and the low PLR groups.Compared with the low PLR group, the high PLR group had a significantly increased risk of in-hospital (RR, 1.95; 95% CI, 1.30-2.91; P = 0.001) and long-term (RR, 1.50; 95% CI, 1.08-2.09; P = 0.01) major adverse cardiovascular events. CONCLUSIONS: Elevated PLR was found to be a predictor of all-cause mortality and cardiovascular events.