Prognostic Role of the Platelet-Lymphocyte Ratio in Acute Ischemic Stroke Patients Undergoing Reperfusion Therapy: A Meta-Analysis

Abstract

Background: Both inflammation and thrombotic/hemostatic mechanisms may play a role in acute ischemic stroke (AIS) pathogenesis, and a biomarker, such as the platelet-to-lymphocyte ratio (PLR), considering both mechanisms may be of clinical utility.

Objectives: This meta-analysis sought to examine the effect of PLR on functional outcomes, early neurological changes, bleeding complications, mortality, and adverse outcomes in AIS patients treated with reperfusion therapy (RT).

Design: Systematic Review and Meta-Analysis.

Data sources and methods: Individual studies were retrieved from the PubMed/Medline, EMBASE and Cochrane databases. References thereof were also consulted. Data were extracted using a standardised data sheet, and systematic reviews and meta-analyses on the association of admission (pre-RT) or delayed (post-RT) PLR with defined clinical and safety outcomes were conducted. In the case of multiple delayed PLR timepoints, the timepoint closest to 24 hours was selected.

Results: Eighteen studies (n=4878) were identified for the systematic review, of which 14 (n=4413) were included in the meta-analyses. PLR collected at admission was significantly negatively associated with 90-day good functional outcomes (SMD=-.32; 95% CI = -.58 to -.05; P=.020; z=-2.328), as was PLR collected at delayed timepoints (SMD=-.43; 95% CI = -.54 to -.32; P<.0001; z=-7.454). PLR at delayed timepoints was also significantly negatively associated with ENI (SMD=-.18; 95% CI = -.29 to -.08; P=.001. Conversely, the study suggested that a higher PLR at delayed timepoints may be associated with radiological bleeding and mortality. The results varied based on the type of RT administered.

Conclusions: A higher PLR is associated with worse outcomes after stroke in terms of morbidity, mortality, and safety outcomes after stroke.

Keywords: endovascular therapy; meta-analysis; platelet-lymphocyte ratio; reperfusion therapy; stroke.

Figure 1.

PRISMA Diagram. Note: The PRISMA flowchart shows the main characteristics of the included studies. Outcomes for which a meta-analysis could successfully be carried out also have the number of patients shown. Abbreviations: mRS=Modified Rankin Scale; SAI=Stroke Associated Infection; SAP=Stroke Associated Pneumonia; sICH=symptomatic intracerebral hemorrhage; PH=Parenchymal Hematoma; PLR=Platelet-Lymphocyte Ratio; N=Number of Included Studies; n=number of patients.

Figure 2.

Forest plots showing association of platelet lymphocyte ratio (PLR) with good functional outcomes. Abbreviations: GFOs=Good Functional Outcomes; PLR=Platelet-Lymphocyte Ratio; IVT=Intravenous Thrombolysis; EVT=Endovascular Thrombectomy.

Figure 3.

Forest plots showing association of platelet lymphocyte ratio (PLR) with radiological bleed and early neurological improvement (ENI). Abbreviations: PLR=Platelet-Lymphocyte Ratio; IVT=Intravenous Thrombolysis; EVT=Endovascular Thrombectomy; ENI=Early Neurological Improvement.

Figure 4.

Funnel Plots for each meta-analysis. Note: Funnel plots for each meta-analysis. A: Admission PLR association with Good Functional Outcomes; B: Delayed PLR association with Good Functional Outcomes; C: Admission PLR association with Radiological Bleed; D: Admission PLR association with ENI.