To our knowledge, no other studies have explored the association between NAR and POP after aSAH. In this study, we found that higher NAR at admission was related to POP in aSAH patients. Interestingly, after adjusting for traditional risk factors such as age, clinical grade,NAR remained an independent factor of POP.
POP is a common condition with possible severe complications following surgical treatment of aSAH patients with 30 days, which directly affects prognosis.[13, 24, 32] Although there are variety of classic predictors of POP,most still is based on clinical parameters including age༌WFNS grade. In recent years, the relevant biomarkers were used to predict the occurrence of POP after aSAH༌such as cerebral lactate and NLR.[2, 20] We suppose that hematology inspection data might be more reflecting and objective subtle changes in patients, especially, when both hematology indicator were administered in combination.
Previous studies have shown that NAR was an inflammatory marker for cancers, sepsis,in-stent restenosis undergoing carotid angioplasty and STEMI,[3, 12, 25, 30] but the underlying mechanisms remain unclear. Studies have shown that neutrophil counts increase as part of the post-stroke immunodepression phenomenon,[8, 21, 29] activated by the sympathetic nervous system and hypothalamic-pituitary-adrenal axis.[7, 9] Serum albumin is not only the most abundant antioxidant in the living body༌but also an inflammatory biomarker that involved in systemic inflammation through high levels of proinflammatory cytokines and growth factors.[5, 16, 22] In fact, studies have shown that albumin therapy can be used to enhance organ function, minimizes complications in aSAH patients, and may lead to a better outcome.[6, 28, 31] We argue that pathological mechanisms of elevated NAR include both an excessive neuroinflammation response indicated by increased neutrophil as well as albumin decrease might resulted in the susceptibility to infection such as POP.
In this study, our results showed that the severity of aSAH could be associated with NAR and POP, the levels of NAR in aSAH patients with higher WFNS grade and mFisher grade were higher than those with lower WFNS grade and mFisher grade. Besides, the incidence of pneumonia in aSAH patients with higher WFNS grade were higher than those with lower WFNS grade. Some of these studies demonstrated a close relationship between POP and severe aSAH.[4, 34]
Furthermore, ROC curves were applied to discriminate between patients with aSAH at risk of POP. We actually observed that NAR was capable of predicting the occurrence of POP significantly. Moreover, its predictive abilities were comparable to the NLR and WFNS grade. Although inflammatory conditions may be dynamically changing during the early acute period, our findings suggest that the NAR may be potent enough to predict POP .
The present study has a number of limitations which have to be acknowledged. The study is a retrospective single-center analysis which the possibility of selection bias may exist, thus, the generalisation of the results to clinical conditions should be considered with caution. In addition, We further examine whether NAR changed over time are correlated with the onset of POP.