The Neutrophil to Lymphocyte Ratio in Poststroke Infection: A Systematic Review and Meta-Analysis

Abstract

Ischemic and hemorrhagic strokes have multiple downstream consequences for patients. One of the most critical is poststroke infection (PSI). The goal of this systematic review and meta-analysis was to critically evaluate the literature regarding the use of the neutrophil to lymphocyte ratio (NLR) as a reliable means to detect early PSI development, particularly poststroke pneumonia (PSP) development to help clinicians institute early interventions and improve outcomes. The following were the inclusion criteria: (1) cross-sectional, case-control, and cohort studies; (2) studies comparing NLR data from PSI or PSP patients to controls; and (3) studies with a control group of stroke patients without infection. There was not any language or publication preference. The Newcastle-Ottawa Scale was used by two writers to assess the quality of the included studies. We assessed the certainty of the associations with GRADE methods. Web of Science, PubMed, and Scopus were searched, and 25 studies were included in the qualitative review. Among them, 15 studies were included in the meta-analysis. Standardized mean difference (SMD) was reported with a 95% confidence interval (CI) for the NLR levels. Patients with PSI had significantly higher NLR levels than stroke patients without infection ( SMD = 1.08 ; CI 95 % = 0.78 ‐ 1.39 , P value < 0.001). In addition, the NLR levels of the stroke patients with pneumonia were significantly higher than those without pneumonia ( SMD = 0.98 ; CI 95 % = 0.81 ‐ 1.14 , P value < 0.001). However, data extracted from the qualitative review suggested that NLR could not predict urinary tract infection, sepsis, or ventriculitis in stroke patients. Our study indicated that NLR could be recommended as an inexpensive biomarker for predicting infection, particularly pneumonia, in stroke patients. It can help clinicians institute early interventions that can reduce PSI and improve outcomes.

The prognostic value of neutrophil-to-lymphocyte ratio in patients with traumatic brain injury: A systematic review

“…Beyond the TBI, NLR was assessed in other neurological conditions, such as stroke. Khanzadeh et al conducted a meta-analysis of 15 studies to evaluate using NLR to detect early poststroke infection (PSI) ( 48 ). They found significantly higher NLR levels in stroke patients with PSI compared to those without it (SMD = 0.98; 95% CI = 0.81–1.14; p < 0.001); however, the levels were comparable in terms of poststroke ventriculitis, sepsis, and urinary tract infections ( 48 ).…”

“…Khanzadeh et al conducted a meta-analysis of 15 studies to evaluate using NLR to detect early poststroke infection (PSI) ( 48 ). They found significantly higher NLR levels in stroke patients with PSI compared to those without it (SMD = 0.98; 95% CI = 0.81–1.14; p < 0.001); however, the levels were comparable in terms of poststroke ventriculitis, sepsis, and urinary tract infections ( 48 ). In another meta-analysis of 3641 acute ischemic stroke patients -who received intravenous thrombolysis-, higher NLR levels were linked to higher odds of hemorrhagic transformation (OR = 1.33; 95 % CI = 1.14–1.56; p < 0.001) and poor 90-day functional outcome (OR = 1.64; 95 % CI = 1.38–1.94; p < 0.001) ( 49 ).…”

Systemic innate myeloid responses to acute ischaemic and haemorrhagic stroke

“…In ICH and ischaemic stroke patients, high NLR at admission is predictive of poor 90-day outcome and haemorrhagic transformation respectively [156,157]. Further studies in ischaemic stroke patient cohorts have shown increased NLR scores strongly relate to infection, poor outcome, and mortality at 3 months [158][159][160]. Therefore, one may conclude that high neutrophil counts, particularly when coupled with lymphopenia, could have a detrimental role in the recovery from brain injury.…”

Low Lymphocyte-to-Monocyte Ratio as a Possible Predictor of an Unfavourable Clinical Outcome in Patients with Acute Ischemic Stroke after Mechanical Thrombectomy

“…Based on the current knowledge about the complex pathophysiology of AIS, one crucial prognostic factor for the clinical outcome of AIS patients is the systemic inflammatory response of the organism [ 4 ]. Disruption of the integrity of the blood-brain barrier (BBB) caused by stroke-related brain injury and subsequent release of chemoattractants into the bloodstream lead to recruitment of stimulated peripheral leukocytes into the ischemic tissue [ 5 ]. The innate immune system responds by initially sending neutrophils to the damaged brain tissue.…”

“…The diagnostic and prognostic utilities of these ratios have been observed in several inflammation-related diseases, including cancer, type 2 diabetes mellitus (T2DM), diabetic kidney injury, nonalcoholic fatty liver disease, inflammatory bowel disease, epilepsy, Guillain-Barré syndrome, and COVID-2019 [ 9 , 11 – 17 ]. Furthermore, according to recent studies, these parameters are predictive markers for the development of poststroke complications, including early neurological deterioration and poststroke depression [ 5 , 18 ]. Moreover, from a practical point of view, a complete blood count analysis is one of the quickest, simplest, most accessible, and most economical laboratory tests.…”