The Prognostic Value of Neutrophil-to-Lymphocyte Ratio in Patients With Aneurysmal Subarachnoid Hemorrhage: A Systematic Review and Meta-Analysis of Observational Studies

Abstract

The neutrophil–to-lymphocyte ratio (NLR), as an essential systemic inflammation factor, has been widely used as a prognostic indicator in various diseases, such as malignant tumors, cardiovascular disease, and intracranial hemorrhage. An increasing number of studies have believed that NLR is a valuable predictor of prognosis for patients with aneurysmal subarachnoid hemorrhage (aSAH). However, these results remain controversial. In the current study, we planned to carry out a systematic review and meta-analysis to investigate the association between NLR and poor outcome, and the occurrence of delayed cerebral ischemia (DCI). We carried out a comprehensive search for published literatures on PubMed, EMBASE, Cochrane Library, and Web of Science databases from inception to April 1, 2021. We conducted an assessment of all included studies based on the principles proposed in the Newcastle-Ottawa Quality Assessment Scale (NOS). Poor outcome and the occurrence of DCI were considered as the main outcome measure. We calculated the pooled odds ratio (OR) and corresponding 95% confidence interval (CI) to examine the strength of the association of NLR with poor outcome or the occurrence of DCI. We strictly selected a total of 10 studies comprising 4,989 patients. Nine studies reported the association between NLR and poor outcome, and five studies reported the association between NLR and the occurrence of DCI. The pooled results indicated higher NLR was significantly associated with both poorer outcomes (OR = 1.32, 95%CI 1.11–1.57; P = 0.002, I2 = 87%), and the occurrence of DCI (OR = 1.72, 95%CI 1.22–2.41; P = 0.002, I2 = 82%) in aSAH patients. The NLR is a valuable indicator of inflammation to independently predict poor outcome and occurrence of DCI after aSAH, where a higher NLR is significantly associated with poor outcomes and occurrence of DCI. These findings suggest that the NLR can help clinicians evaluate the prognosis and identify potentially severe patients early, which may contribute to better management and improve poor prognosis of aSAH patients.

Red-cell distribution width as a prognostic marker for aneurysmal subarachnoid hemorrhage: A systematic review and meta-analysis

“…Regarding this issue, other new biomarkers have been studied, such as neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and systemic inflammatory response index (SIRI). 57 , 58 , 59 Unfortunately, only a few studied these parameters alongside RDW, making a comparison between them difficult. One study by Huang et al compared RDW directly with NLR in aSAH patients.…”

Neutrophil-to-Lymphocyte Ratio Is Associated With Circumferential Wall Enhancement of Unruptured Intracranial Aneurysm

“…Our study confirmed that NLR was significantly higher in patients with ruptured IAs than those with unruptured IAs, as shown in previous studies ( 28 , 29 ). The elevated NLR at admission has been shown to predict the unfavorable functional outcome, delayed cerebral ischemia, in-hospital mortality, and rebleeding in patients with aneurysmal subarachnoid hemorrhage ( 23 , 27 , 29 – 31 ). An elevated NLR was also associated with aneurysm size in patients with unruptured IAs ( 29 ).…”

“…Neutrophil-lymphocyte ratio (NLR) indicates the inflammation status in clinical practice, calculated as the absolute neutrophil count divided by the absolute lymphocyte count in the routine blood test. Elevated NLR predicts poor outcomes in patients with acute ischemic stroke, spontaneous intracerebral hemorrhage, and SAH resulting from ruptured IA ( 20 – 23 ). In this study, we aimed to investigate the association of NLR as a peripheral blood inflammatory marker with AWE on HR-VWI in patients with unruptured IA.…”

Prognostic significance of combined score of fibrinogen and neutrophil-lymphocyte ratio for functional outcome in patients with aneurysmal subarachnoid hemorrhage

“…Although several previous studies had identified NLR as a biomarker for worse functional outcomes after aSAH ( 7 , 8 , 15 ), the specific relationship among them remained obscure and may be due to the following reasons. Unfavorable outcomes may be attributed to complications, such as delayed cerebral ischemia (DCI) or cerebral vasospasm (CVS).…”