Role of neutrophil-lymphocyte ratio in the prognosis of acute ischaemic stroke after reperfusion therapy : a systematic review and meta-analysis

Background: Inflammation may mediate response to acute reperfusion therapy (RT) in acute cerebral ischaemia. Neutrophil-lymphocyte ratio (NLR), an inflammatory biomarker, may play an important role in acute ischaemic stroke (AIS) prognostication. Objective: This meta-analysis sought to examine the effect of NLR on functional outcomes, mortality and adverse outcomes in AIS patients receiving RT. Methods: Individual studies were retrieved from PubMed/Medline, EMBASE and Cochrane databases. Data were extracted using a standardised data sheet and meta-analysis on association of admission (pre-RT) or delayed (post-RT) NLR with clinical/safety outcomes after RT was conducted. Results: Thirty-five studies (n = 10 308) were identified for the systematic review with 27 (n = 8537) included in the meta-analyses. Lower admission NLR was associated with good functional outcomes (GFOs), defined as 3-month modified Rankin scale (mRS) 0–2 (SMD = −.46; 95% CI = −.62 to −.29; P <.0001), mRS 0–1 (SMD = −.44; 95% CI = −.66 to −.22; P <.0001) and early neurological improvement (ENI) (SMD = −.55; 95 %CI = −.84 to −.25; P <.0001). Lower delayed admission NLR was also associated with GFOs (SMD = −.80; 95%CI = −.91 to −.68; P <.0001). Higher admission NLR was significantly associated with mortality (SMD =.49; 95%CI =.12 to.85; P =.009), intracerebral haemorrhage (ICH) (SMD =.34; 95% CI =.09 to.59; P =.007), symptomatic ICH (sICH) (SMD =.48; 95% CI =.07 to.90; P =.022) and stroke-associated infection or pneumonia (SMD =.85; 95% CI =.50, 1.19; P <.0001). Higher delayed NLR was significantly associated with sICH (SMD = 1.40; 95% CI =.60 to 2.19; P =.001), ICH (SMD =.94; 95% CI =.41 to 1.46; P <.0001) and mortality (SMD = 1.12; 95% CI =.57 to 1.67; P <.0001). There were variations in outcomes across RT groups. Conclusion: Higher admission or delayed NLR is significantly associated with worse morbidity, mortality and safety outcomes in AIS patients receiving RT.