In the International Study on Cerebral Vein and Dural Sinus Thrombosis (ISCVT), male gender, age > 37 years old, mental status disturbance, coma, thrombosis of the deep venous system, intracranial hemorrhage, malignancy, and infection of the central nervous system were independently associated with adverse outcome at last follow-up [15]. Our study showed that PNI was a significant and independent predictor of poor prognosis in non-chronic CVST patients.
Current research supports the link between inflammation and the incidence of CVST [16, 17]. A number of studies appeared to reinforce the biological plausibility behind inflammation and the prognosis of cerebral venous thrombosis [18, 19]. The lymphocyte count is an indicator that mediates cellular immunity. It is worth noting that some studies supported the use of lymphocyte count as a prognostic indicator. Lymphocytes are involved in cellular immunity of various cancers and are related to cancer prognosis [20]. In addition, previous study has shown that lymphocyte count is a predictive factor of adverse outcome in patients with AIS [21]. In animal models, immunosuppression induced by stroke could lead to lymphopenia and changes in the ratio of helper T cell [22, 23]. Similarly in human studies, it had also been observed that peripheral blood lymphocytes decreased after stroke, particular in the acute phase [24, 25]. Therefore, lower lymphocyte count may be a predictor of adverse outcome. The relationship between lymphocyte count and the outcome of CVST has been confirmed in previous studies, such as platelet to lymphocyte ratio (PLR), lymphocyte to monocyte ratio (LMR) and neutrophil to lymphocyte ratio (NLR) [26–28].
Hypoalbuminemia is a comprehensive result of inflammation and insufficient intake of protein and calories in patients with chronic diseases. In different clinical settings, hypoalbuminemia has been shown to be a sign of poor prognosis [29–31]. Considering that albumin is a negative acute phase protein, its synthesis rate is affected by nutrition and inflammation [32]. More and more evidence shows that as the severity of inflammation increases, serum albumin levels gradually decrease [33, 34]. Albumin combined with nitric oxide (NO) free radicals has anticoagulant and antithrombotic effects. Due to the increase in the concentration of free lysophospholipids, hypoalbuminemia may affect blood viscosity and endothelial cell function [35]. However, serum albumin is not a good indicator of nutrition observation because it is greatly affected by fluid transfer [29]. Many different factors affect serum albumin levels and have shown a lack of sensitive and specific indicators of nutritional status [36].
As for PNI, it combines the lymphocyte count and albumin concentration, reflecting the nutrition, inflammation and immunity status. Therefore, compared with the above single factors, PNI is more stable and representative. The PNI was originally reported to be used to evaluate the immune and nutritional status of patients undergoing gastrointestinal tract surgery [14, 37, 38]. Subsequently, PNI has been widely used in prognostic evaluation of a variety of cancers and transplant operations, as well as for patients with various diseases such as myocardial infarction, acute type A aortic dissections and AIS patients receiving intravenous thrombolysis (IVT) [10, 11, 39, 40].
This study has further shown that lower PNI increased the risk of poor outcome in patients attributable to acute/subacute patients with CVST. Additionally, the findings from nomograms by stepwise logistic regression analyses suggested that age, coma, intracerebral hemorrhage, straight sinus involvement and PNI were also predictors of adverse outcome in acute/subacute patients with CVST, which further supported the results from multivariate logistic regression analyses. Therefore, the PNI created by combining serum albumin concentration and lymphocyte counts have the ability to assess the nutritional, inflammatory and immune status of patients with acute/subacute CVST. Considering that patients with lower PNI scores in this study have a significantly higher incidence of poor prognosis, it can be considered that appropriate evaluation and implementation of measures to improve nutritional status will help improve the outcome of patients with acute/subacute CVST. Further prospective studies are required to verify this hypothesis.
PNI is easy to obtain because it is calculated using objective laboratory test data. This makes it easy for our achievements to be translated into daily practice. However, several potential limitations should be acknowledged in the present study. First, it is a single-centre study and the sample size included in our study is relatively small. This association in the present study also needs to be confirmed and verified in larger multicenter prospective cohort studies. Second, compared with arterial stroke, it is difficult to determine the exact time of onset in patients with CVST.
In summary, our study suggested that lower PNI was a potential dangerous factor in unfavorable functional outcome of patients with acute/subacute CVST.