Prognostic value of neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio in acute pulmonary embolism: a systematic review and meta-analysis.

Introduction: Neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) have been reported to predict prognosis of acute pulmonary embolism (PE). However, the prognostic value of NLR and PLR remained inconsistent between studies. The aim of this meta-analysis was to assess the prognostic role of NLR and PLR in acute PE.

Evidence Acquisition: We systematically searched Pubmed, Embase, Web of Science and CNKI for relative literature up to March 2017. The pooled statistics for all outcomes were expressed as odds ratio (OR) and 95% confidence intervals (95% CI). The statistical analyses were performed using Review Manager 5.3.5 analysis software and Stata software.

Evidence Synthesis: Totally 7 eligible studies consisting of 2323 patients were enrolled in our meta-analysis. Elevated NLR was significantly associated with overall (short-term and long-term) mortality (OR 10.13, 95% CI 6.57-15.64, P<0.001) and short-term (in-hospital and 30 days) mortality (OR 8.43, 95% CI 5.23-13.61, P<0.001). And elevated PLR was significantly associated with overall mortality (OR 6.32, 95% CI 4.52-8.84, P<0.001), short-term mortality (OR 6.69, 95% CI 2.86-15.66, P<0.001) and long-term mortality (OR 6.11, 95% CI 3.90-9.55, P<0.001).

Conclusions: Our meta-analysis revealed that NLR and PLR are promising biomarkers in predicting prognosis in acute PE patients. We suggest NLR and PLR be used routinely in the PE prognostic assessment.