Letter: Systemic Immune-Inflammation Index Predicts Delayed Cerebral Vasospasm After Aneurysmal Subarachnoid Hemorrhage

Abstract

To the Editor:We congratulate Geraghty et al 1 and their team for their finding that SII index was an independent predictor of delayed cerebral vasospasm in aneurysmal subarachnoid hemorrhage (aSAH). Delayed cerebral ischemia (DCI) is one of the common complications after aSAH contributing to poor functional outcomes. 2 Until now, cerebral vasospasm is still widely accepted as the primary cause to DCI after aSAH. 3 Therefore, identification of easily accessible and reliable predictors for vasospasm could bring improvement in patient risk stratification and future intervention. However, several issues in this great work still need to be addressed.First, the authors did not set up exclusion criteria during the patient collection. Other conditions, such as thrombocytopenia, lymphoma, infections, or autoimmune disease cancer, might also affect the SII index. These comorbidities should be taken into consideration in the future prospective studies. Second, neutrophil-to-lymphocyte ratio (NLR), another readily available and convenient biomarker, has been reported to independently predict development of DCI (odds ratio [OR] 1.7, 95% CI 1.1-2.5, P = .008) 4 and unfavorable functional outcomes (OR 1.014, 95% CI 1.001-1.027, P = .028). 5 The main difference between SII and NLR is the platelet count when calculating the index. In this study, Geraghty et al reported that NLR also independently predicted vasospasm with an OR of 1.088 (95% CI 1.032-1.147, P = .002) in the multivariable logistic regression analysis. However, in the receiver operating characteristic curves, the authors only compared SII and the multivariable SII model with modified Fisher scale, with the NLR not included. Third, the authors reported the optimal cutoff of SII in the receiver operating characteristic curve for distinguishing between patients with or without vasospasm. It would provide more information if the association between the admission characteristics and SII was analyzed with the aim to detect the predictors of elevated SII.In all, we thank the authors for their original work and their detection of a new promising index for predicting vasospasm in patients with aSAH.

In Reply: Systemic Immune-Inflammation Index Predicts Delayed Cerebral Vasospasm After Aneurysmal Subarachnoid Hemorrhage

“…We agree with the comments by Chen et al 1 that much further work remains to be performed. Although SII incorporates changes in platelets into its calculation, SII can further be influenced by potentially inflammatory conditions such as infection, autoimmune disease, or cancer.…”

“…We would like to thank Chen et al 1 for their positive, thoughtful comments related to our recent publication on this topic. 2 Delayed cerebral vasospasm (DCV), especially when symptomatic and associated with delayed cerebral ischemia (DCI), is a feared complication of aneurysmal subarachnoid hemorrhage (aSAH) associated with considerable morbidity and mortality.…”