Research Paper Volume 16, Issue 10 pp 8810—8821

Systemic immune-inflammation index upon admission correlates to post-stroke cognitive impairment in patients with acute ischemic stroke

Yongqing Cheng1,2, *, , Honghong Zhu3, *, , Changxia Liu1, *, , Lei Li1, , Fangjia Lin1, , Yan Guo1, , Cong Gu1, , Dingming Sun1, , Yang Gao1, , Guojun He1, , Shifu Sun1, , Shouru Xue2, ,

  • 1 Department of Neurology, The Yancheng Clinical College of Xuzhou Medical University, The First People’s Hospital of Yancheng, Yancheng 224000, Jiangsu, China
  • 2 Department of Neurology, The First Affiliated Hospital of Soochow University, Suzhou 215006, Jiangsu, China
  • 3 Department of Rheumatology and Immunology, The Yancheng Clinical College of Xuzhou Medical University, The First People’s Hospital of Yancheng, Yancheng 224000, Jiangsu, China
* Equal contribution and shared first authorship

Received: November 27, 2023       Accepted: April 9, 2024       Published: May 20, 2024      

https://doi.org/10.18632/aging.205839
How to Cite

Copyright: © 2024 Cheng et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Abstract

Background: The purpose of this prospective study was to evaluate the association of systemic immune-inflammation index (SII) and systemic inflammation response index (SIRI), with PSCI in patients with acute ischemic stroke (AIS).

Methods: First-onset AIS patients were consecutively included from January 1, 2022 to March 1, 2023. The baseline information was collected at admission. Fasting blood was drawn the next morning. Cognitive function was assessed by the Montreal Cognitive Assessment (MoCA) 3 months after onset. Logistic regression analysis was performed to explore the correlation between SII, SIRI, and PSCI. Receiver operating characteristic (ROC) was conducted to evaluate the predictive ability of SII.

Results: 332 participants were recruited, and 193 developed PSCI. Compared with patients without PSCI, the patients with PSCI had higher SII (587.75 (337.42, 988.95) vs. 345.66 (248.44, 572.89), P<0.001) and SIRI (1.59 (0.95, 2.84) vs. 1.02 (0.63, 1.55), P=0.007). SII and SIRI negatively correlated with MoCA scores (both P<0.05). The multivariable logistic regression analysis indicated that SII was independently associated with PSCI (P<0.001), while SIRI was not. The optimal cutoff for SII to predict PSCI was 676.83×109/L.

Conclusions: A higher level of SII upon admission was independently correlated to PSCI three months later in AIS patients.

Introduction

According to the 2019 Global Burden of Disease (GBD) study, stroke remains the second leading cause of death worldwide [1]. As a prevalent non-motor complication of AIS, PSCI has been confirmed to be related to poor outcomes [2]. Early identification and intervention of PSCI can avoid the progressive deterioration of cognitive function and effectively improve the prognosis of patients.

Recent studies have suggested potential mechanistic links between inflammation, stroke and dementia [3, 4]. Neutrophils, lymphocytes, platelets, and monocytes are essential immune system elements [5]. The balance between innate and adaptive immunity can be better indicated by the systemic inflammation response index (SIRI) and the systemic immune-inflammation index (SII), which are calculated from the counts of neutrophils, platelets, monocytes, and lymphocytes [6]. The diagnostic and predictive efficacy of cardiovascular diseases, tumors, and inflammatory diseases has been confirmed by previous research [710]. Besides, another research has shown a link between the SII and a high incidence of dementia in the general public [3]. Recent findings have also confirmed the correlation between SII and hemorrhagic transformation as well as poor prognosis in AIS patients [6]. Meanwhile, the relationship between SII or SIRI and PSCI remains uncertain. Therefore, we designed this prospective cohort study to explore the association of SII and SIRI with PSCI and further evaluate their predictive value for PSCI.

Results

Between January 2022 and March 2023, a consecutive screening of 574 patients with AIS was performed. We excluded 242 patients on the basis of exclusion criteria and incomplete follow-up data. Finally, the study enrolled 332 participants, 203 of whom were male (Figure 1). The mean age of the participants was 68 years old, with an interquartile range of 58-76, and 58.13% of them developed PSCI three months later. The tertile levels of SII and SIRI were as follows: Tertile 1 (76.67≤SII<335.02), Tertile 2 (335.02≤SII<683.03), Tertile 3 (683.03≤SII≤5048.81) and Tertile 1 (0.02≤SIRI<0.95), Tertile 2 (0.95≤SIRI<1.79), Tertile 3 (1.79≤SIRI≤17.17). Violin plots about the distribution of SII and SIRI in subgroups are shown in Figures 2, 3.

Flow diagram.

Figure 1. Flow diagram.

Violin plot about the distribution of SII and SIRI in the PSCI and nonPSCI subgroups.

Figure 2. Violin plot about the distribution of SII and SIRI in the PSCI and nonPSCI subgroups.

Violin plot about the distribution of SII and SIRI in the PSCI and nonPSCI subgroups.

Figure 3. Violin plot about the distribution of SII and SIRI in the PSCI and nonPSCI subgroups.

Correlation between SII, SIRI, and MoCA score

Figures 4, 5 show the results of Spearman’s analysis of the correlation between SII and MoCA and SIRI and MoCA scores, respectively. The negative correlations of SII and SIRI with MoCA scores were clarified in the results (r=-0.143, P=0.007 and r=-0.167, P=0.002, respectively).

Spearman correlation analysis between SII, SIRI and MoCA score.

Figure 4. Spearman correlation analysis between SII, SIRI and MoCA score.

Spearman correlation analysis between SII, SIRI and MoCA score.

Figure 5. Spearman correlation analysis between SII, SIRI and MoCA score.

Contrasts in characteristics among the PSCI and non-PSCI subgroups

The cognitive function of participants was assessed using the MoCA scale three months after the onset, resulting in the diagnosis of PSCI in 193 patients. The participants were segregated into subgroups based on their cognitive function. Table 1 presents the differences in characteristics between the PSCI and non-PSCI subgroups. The results indicated that patients with PSCI had higher levels of age, NIHSS, cerebral infarct volume, Fazekas score, FPG, TG, Neutrophils, monocyte, SII, SIRI (all P<0.005), as well as lower levels of education, HDL, lymphocytes, MoCA score (all P<0.005). Moreover, patients with PSCI also had higher proportions of atrial fibrillation (P=0.027), drinking (P=0.008), and cortical infarction (P=0.003).

Table 1. Characteristics between PSCI group and non-PSCI group.

Baseline characteristicsPSCI (n=193)Non-PSCI (n=139)P
Demographics
Male, n (%)115 (59.6)88 (63.3)0.496
Age, median (IQR) (years)72.0 (64.0, 79.0)61.0 (52.0, 69.0)<0.001
BMI, median (IQR) (Kg/m2)24.49 (22.29, 27.02)24.77 (22.49, 26.93)0.465
Education level, n (%)<0.001
Illiterate50 (25.9)7 (5.0)
Primary school78 (40.4)50 (36.0)
Secondary school or above65 (33.7)82 (59.0)
Medical history, n (%)
Hypertension131 (67.9)80 (57.6)0.064
Diabetes mellitus64 (33.2)38 (27.3)0.279
Coronary artery disease27 (14.0)20 (14.4)0.920
Atrial fibrillation35 (18.1)13 (9.4)0.027
Smoking73 (37.8)50 (36.0)0.818
Drinking81 (42.0)38 (27.3)0.008
Clinical characteristics
NIHSS on admission, median (IQR)6.0 (2.0, 10.5)3.0 (2.0, 6.0)<0.001
Cerebral infarct volume, median (IQR) (cm3)2.3 (0.62, 6.50)0.94 (0.40, 2.30)<0.001
Cortical infarction, n (%)96 (49.7)46 (33.1)0.003
carotid plaque, n (%)171 (88.6)118 (84.9)0.408
Carotid artery stenosis, n (%)58 (30.1)44 (31.7)0.81
Fazekas score, median (IQR)4.0 (3.0, 5.0)3.0 (3.0, 4.0)<0.001
Stroke etiology, n (%)0.055
LAA113 (58.5)79 (56.8)
Cardioembolism25 (13.0)7 (5.0)
Small-vessel occlusion48 (24.9)46 (33.1)
Undetermined/unclassified7 (3.6)7 (5.0)
Laboratory characteristics
Hcy, median (IQR) (μmol/L)11.40 (8.75, 16.15)11.20 (8.70, 16.80)0.887
FBG, median (IQR) (mmol/L)5.81 (5.08, 8.35)5.17 (4.63, 6.32)<0.001
Uric acid, median (IQR) (μmol/L)325.00 (258.60, 406.15)321.3 (268.10, 382.00)0.58
HbA1c, median (IQR) (%)5.7 (5.4, 6.7)5.7 (5.3, 6.5)0.167
TG, median (IQR) (mg/dL)1.55 (0.98, 2.28)1.37 (1.07, 1.72)0.03
TC, median (IQR) (mmol/L)4.46 (3.68, 5.41)4.37 (3.74, 5.25)0.608
HDL-C, median (IQR) (mmol/L)1.00 (0.86, 1.19)1.09 (0.98, 1.24)0.001
LDL-C, median (IQR) (mmol/L)2.70 (2.17, 3.34)2.63 (2.13, 3.35)0.508
Leukocyte, median (IQR) (109/L)7.04 (5.40, 8.96)6.07 (4.98, 7.52)0.001
Neutrophils, median (IQR) (109/L)4.49 (3.20, 6.77)3.61 (2.78, 4.62)<0.001
Lymphocytes, median (IQR) (109/L)1.47 (1.11, 1.92)1.59 (1.30, 2.01)0.031
Monocyte, median (IQR) (109/L)0.53 (0.42, 0.67)0.48 (0.37, 0.59)0.007
Platelets, median (IQR) (109/L)184.0 (144.5, 241.5)184.0 (136.0, 216.0)0.136
SII, median (IQR) (109/L)587.75 (337.42, 988.95)345.66 (248.44, 572.89)<0.001
SIRI, median (IQR) (109/L)1.59 (0.95, 2.84)1.02 (0.63, 1.55)<0.001
SII tertiles, n (%)<0.001
T147 (24.4)64 (46.0)
T261 (31.6)50 (36.0)
T385 (44.0)25 (18.0)
SIRI tertiles, n (%)<0.001
T148 (24.9)63 (45.3)
T264 (33.2)47 (33.8)
T381 (42.0)29 (20.9)
MoCA, median (IQR)21 (17, 23)27 (26, 27)<0.001
Abbreviations: PSCI, post-stroke cognitive impairment; BMI, body mass index; NIHSS, National Institutes of Health Stroke Scale; LAA, large artery atherosclerosis; Hcy, homocysteine; FPG, fasting plasma glucose; HbA1c, glycosylated hemoglobin A1c; TG, triglyceride; TC, total cholesterol; HDL-C, high-density lipoprotein cholesterol; LDL-C, low-density lipoprotein cholesterol; SII, systemic immune-inflammation index; SIRI, systemic inflammation response index; MoCA, Montreal Cognitive Assessment.

Relationship between SII, SIRI and PSCI

The findings from the logistic regression models with SII and SIRI as continuous variables are presented in Table 2. Results from the univariable logistic regression analysis demonstrated a significant association of PSCI with age, education level, history of atrial fibrillation, history of drinking, NIHSS, infarction volume, cortical infarction, Fazekas score and some laboratory data (including FPG, leukocyte, neutrophils, monocyte, SII, SIRI, TG, and HDL-C) (all P<0.05). After controlling for variables with P<0.1 in the univariable regression analysis, education level (OR=0.258, P=0.011), age (OR=1.089, P<0.001), history of drinking (OR=2.035, P=0.026), NIHSS (OR=1.176, P<0.001), cerebral infarct volume (OR=1.068, P=0.016), cortical infarction (OR=1.064, P=0.034), FPG (OR=1.231, P=0.001), TG (OR=2.193, P<0.001) and SII (OR=1.002, P<0.001) were proved to be independently associated with PSCI in the multivariable regression analysis. Furthermore, SII and SIRI were then entered into the multivariable regression model as tertiles. The findings demonstrated that when the first tertile was taken as a reference, the second and third tertile of SII were both independent risk factors for PSCI (OR=2.355, P=0.021 and OR=10.369, P<0.001, respectively). However, no significant correlation between SIRI and PSCI was found (Table 3).

Table 2. Univariable and multivariable analyses for the potential risk factors associated with PSCI, including SII and SIRI as continuous variables by logistic regression.

Baseline characteristicsUnivariable analysisMultivariable analysis
OR (95%CI)P-valueAdjusted OR (95%CI)P-value
Demographics
Male0.854 (0.545-1.339)0.492
Age1.072 (1.050-1.095)<0.0011.089 (1.059-1.119)<0.001
BMI0.960 (0.896-1.028)0.244
Education level
Illiteratereferencereference
Primary school0.218 (0.092-0.520)0.0010.422 (0.149-1.199)0.105
Secondary school or above0.111 (0.047-0.261)<0.0010.258 (0.090-0.737)0.011
Medical history
Hypertension1.558 (0.991-2.449)0.054
Diabetes mellitus1.319 (0.817-2.128)0.257
Coronary artery disease0.968 (0.518-1.807)0.918
Atrial fibrillation2.147 (1.090-4.231)0.027-0.962
Smoking1.083 (0.689-1.702)0.730
Drinking1.922 (1.201-3.075)0.0062.035 (1.089-3.803)0.026
Clinical characteristics
NIHSS on admission1.171 (1.101-1.246)<0.0011.176 (1.083-1.278)<0.001
Cerebral infarct volume1.077 (1.031-1.125)0.0011.068 (1.012-1.126)0.016
Cortical infarction2.001 (1.273-3.145)0.0031.964 (1.051-3.670)0.034
Carotid atherosclerosis1.383 (0.728-2.629)0.322
Carotid artery stenosis0.928 (0.579-1.487)0.755
Fazekas score1.734 (1.382-2.176)<0.001-0.525
Stroke etiology
LAAReferenceReference
Cardioembolism2.497 (1.029-6.056)0.043-0.602
Small-vessel occlusion0.730 (0.444-1.198)0.213-0.315
Undetermined/unclassified0.699 (0.236-2.072)0.518-0.873
Laboratory characteristics
Hcy1.008 (0.967-1.051)0.704
FPG1.177 (1.073-1.290)0.0011.231 (1.090-1.391)0.001
Uric acid1.001 (0.999-1.003)0.369
HbA1c1.068 (0.926-1.232)0.366
TG1.462 (1.120-1.910)0.0052.193 (1.471-3.270)<0.001
TC1.098 (0.922-1.307)0.295
HDL-C0.395 (0.201-0.773)0.007-0.066
LDL-C1.126 (0.880-1.441)0.346
Leukocyte1.181 (1.071-1.302)0.001-0.913
Neutrophils1.268 (1.131-1.421)<0.001-0.828
Lymphocytes0.718 (0.510-1.011)0.058-0.856
Monocyte4.776 (1.539-14.818)0.007-0.599
Platelets1.003 (1.000-1.006)0.076-0.989
SII1.001 (1.001-1.002)<0.0011.002 (1.001-1.002)<0.001
SIRI1.429 (1.189-1,719)<0.001-0.728
Abbreviations: PSCI, post-stroke cognitive impairment; IQR, interquartile range; BMI, body mass index; NIHSS, National Institutes of Health Stroke Scale; LAA, large artery atherosclerosis; Hcy, homocysteine; FPG, fasting plasma glucose; HbA1c, glycosylated hemoglobin A1c; TG, triglyceride; TC, total cholesterol; HDL-C, high-density lipoprotein cholesterol; LDL-C, low-density lipoprotein cholesterol; SII, systemic immune-inflammation index; SIRI, systemic inflammation response index; MoCA, Montreal Cognitive Assessment.

Table 3. Multivariable analyses for the potential risk factors associated with PSCI, including SII and SIRI as tertiles by logistic regression.

Baseline characteristicsMultivariable analysis
Adjusted OR (95%CI)P-value
Demographics
Age1.090 (1.060-1.122)<0.001
Education level
Illiteratereference
Primary school0.448 (0.153-1.313)0.143
Secondary school or above0.264 (0.089-0.780)0.016
Medical history
Hypertension-0.990
Atrial fibrillation-0.880
Drinking2.060 (1.093-3.884)0.025
Clinical characteristics
NIHSS on admission1.188 (1.091-1.295)<0.001
Cerebral infarct volume1.072 (1.014-1.133)0.014
Cortical infarction1.935 (1.016-3.687)0.045
Fazekas score0.386
Stroke etiology
LAAReference
Cardioembolism-0.537
Small-vessel occlusion-0.160
Undetermined/unclassified-0.927
Laboratory characteristics
FPG1.255 (1.104-1.427)0.001
TG2.213 (1.451-3.375)<0.001
HDL-C0.371 (0.137-1.000)0.050
Leukocyte-0.945
Neutrophils-0.991
Lymphocytes-0.870
Monocyte-0.819
Platelets-0.948
SII tertiles
T1reference
T22.355 (1.138-4.877)0.021
T310.369 (4.460-24.107)<0.001
SIRI tertiles
T1reference
T2-0.822
T3-0.572
Abbreviations: PSCI, post-stroke cognitive impairment; BMI, body mass index; NIHSS, National Institutes of Health Stroke Scale; LAA, large artery atherosclerosis; FPG, fasting plasma glucose; TG, triglyceride; HDL-C, high-density lipoprotein cholesterol; SII, systemic immune-inflammation index; SIRI, systemic inflammation response index; MoCA, Montreal Cognitive Assessment.

ROC analysis of SII for predicting PSCI

The diagnostic utility of SII in predicting PSCI was assessed using ROC analysis, with the AUC of 0.659 (P<0.001). (Figure 6). The optimal cutoff value was ≥676.83×109/L, and the sensitivity and specificity were 44.6% and 82.0%, respectively.

Receiver operating characteristic (ROC) curve for SII as a predictor of PSCI.

Figure 6. Receiver operating characteristic (ROC) curve for SII as a predictor of PSCI.

Discussion

The inflammation response has been reported to be crucial in stroke and PSCI pathobiology [11, 12]. Previous studies have revealed that systemic inflammation processes are closely related to endothelial dysfunction, cell death, blood-brain barrier (BBB) disruption, cerebral blood flow autoregulation disorder and platelet aggregation [5, 13]. Studies consecutively showed that PSCI was associated with some inflammatory biomarkers and cytokines [14, 15]. Otherwise, as important primary immune mediators that can release inflammatory signals, infiltrating leukocytes, including neutrophils, monocytes, and lymphocytes, have been reported to be related to stroke and dementia [16, 17]. Previous studies have shown that peripheral neutrophils and neutrophil to lymphocyte ratio (NLR) correlate to poor prognosis and hemorrhagic transformation of ischemic stroke, as well as cerebral small vessel disease and dementia [1820].

The SII and SIRI derived from different blood cells can better reflect the inflammation or immune status than one cell alone. Hu et al. created SII and reported that SII was an effective predictor of poor outcomes of patients after an operation for hepatocellular carcinoma [9]. Meanwhile, SII was also considered to be correlated to unfavorable outcomes of various tumors such as cholangiocarcinoma, lung cancer, gliomas, etc. [10, 21, 22]. Subsequently, there has been an established link between SII and the occurrence and prognosis of chronic heart failure and coronary heart disease [23, 24]. A recent system review showed that elevated SII could significantly increase the risk of vascular disease, including ischemic stroke, hemorrhagic stroke, myocardial infarction, and peripheral arterial disease [7]. According to a recent large-scale general population study, elevated SII and SIRI could increase the incidence of stroke and all-cause death [25]. In addition, SII on admission was reported to be positively associated with symptomatic intracranial hemorrhage after endovascular treatment in AIS patients with large vessel occlusion [24]. Recently, several research have confirmed the potential relationship between SII and cognitive impairment. According to a retrospective study, elevated SII was closely related to the occurrence of postoperative cognitive decline [26]. Another research also showed a strong correlation between SII and cerebral small vessel disease (CSVD) and cognitive impairment [27]. Therefore, we speculate that SII and PSCI might have a potential relationship. However, there are few reports on the correlation between them. In this research, we discovered that SII was independently correlated to PSCI and might be used as a valid predictor.

The specific mechanisms for the association between SII and PSCI are not yet well understood. Nevertheless, it is hypothesized that blood-brain barrier disruption, endothelial dysfunction, CVSD, and neuroinflammation could have significant implications [11, 28]. Many studies have shown that neutrophils, platelets, and lymphocytes, essential components of SII, were related to endothelial dysfunction and blood-brain barrier disruption [17, 7]. Neutrophils play a negative role by releasing reactive oxides, synthesizing cytokines, intercellular adhesion molecules, and other inflammatory mediators, while platelets secrete pro-inflammatory cytokines and growth factors. [2931]. Furthermore, accumulating evidence has shown that increased SII levels are related to more severe CSVD, which plays a crucial role in cognitive impairment [32]. A community-based population study has demonstrated that individuals with a higher SII had an increased risk of moderate-to-severe enlarged perivascular space (EPVS) and modified white matter hyperintensity (WMH) burden [19]. In addition, peripheral inflammation can penetrate the BBB and induce central neuroinflammation, ultimately contributing causally to cognitive impairment [33]. Emerging evidence has suggested that neuroinflammation plays an active role rather than being passive activation in the pathogenesis of cognitive impairment [13, 34].

Our study confirmed the potential association of SII with PSCI. Nevertheless, some limitations should be noted. First, a few patients with severe aphasia, dysarthria or disturbance of consciousness were not included, which could lead to bias. Second, although we excluded patients with previous stroke, it is difficult to guarantee that the cognitive impairment was exclusively stroke-related because we could not accurately assess pre-stroke cognitive function. Third, we only measured SII and SIRI levels at admission and MoCA scores three months after stroke. The lack of serial detections for levels of SII, SIRI, and cognitive performance may have obscured any potential impact of treatment interventions on the noted correlation. Fourth, we could not rule out the possible impact of some potential risk factors we did not measure, such as ApoE status. Finally, the single center and restricted sample size limit the generalization of the results of our study, and the predictive effect of SII for PSCI in this study was statistically significant but not strong enough.

Conclusions

The potential correlation between SII and PSCI was confirmed by our study. A high level of SII at admission might be an effective predictor of PSCI. Further exploration of the potential mechanism might provide new targets for PSCI treatment.

Materials and Methods

Patient enrollment

This was a prospective cohort study conducted in the First People’s Hospital of Yancheng. The participants were consecutively screened from inpatient department between January 1, 2022, and March 1, 2023. Patients were enrolled if they met the following criteria: (1) ≥ 18 years old, (2) met the World Health Organization diagnostic criteria for AIS confirmed by neuroimaging, (3) admission within seven days of symptom onset, (4) first stroke. Exclusion criteria were as follows: (1) with pre-existing cognitive disorder from diverse diseases, (2) with neurological dysfunctions that may affect cognitive evaluation, such as hearing impairment, aphasia or dysarthria, (3) with diseases which might affect inflammatory conditions, such as blood disease, acute infection, malignant tumors, or trauma, (4) intake of antibiotics, psychotropic or nootropics medications within three months.

Baseline clinical and laboratory data

Clinical and laboratory data were collected in a manner similar to that described in our other article [35]. On admission, we used a standard questionnaire to collect clinical data and to assess the presence of pre-existing cognitive disorder. Baseline demographics (gender, age, education, body mass index (BMI), history of smoking and drinking, as well as medical history (diabetes, hypertension, atrial fibrillation, and coronary artery disease) were collected. We classified the patients into three education levels: those with less than one year of education were classified as illiterate, those with one to six years of education were classified as primary school, and those with more than six years were classified as secondary school or above. The etiology and severity of stroke were determined according to the Trial of Org 10172 in Acute Stroke Treatment (TOAST) criteria and National Institutes of Health Stroke Scale (NIHSS), respectively. Fasting blood samples were obtained from all patients the morning after admission and processed and recorded by a single laboratory physician. The laboratory data included glycosylated hemoglobin A1 (HbA1c), fasting plasma glucose (FPG), uric acid (UA), peripheral blood cell counts, triglyceride (TG), total cholesterol (TC), low-density lipoprotein (LDL), high-density lipoprotein (HDL), and homocysteine (Hcy). We calculated SII versus SIRI using the following formula: platelet count × neutrophil count/lymphocyte count, neutrophil count × monocyte count / lymphocyte count, respectively [9, 25]. All blood laboratory assessments were conducted in the hospital’s clinical laboratory. An auto-analyzer (XN-1000, Sysmex, Kobe, Japan) analyzed all blood cell counts, and other profiles were assessed with an automated biochemical analyzer.

All participants underwent brain MRI scans within 72 hours after admission, and imaging data were collected and analyzed by a doctor from the imaging department. The severity of white matter hyperintensities was assessed using the Fezakas scores, which ranges from 0 to 6. The infarct volume was calculated by multiplying the infarct area of each slice by the slice thickness on the DWI sequence and then summing [36]. The carotid plaque and stenosis were evaluated by carotid ultrasound or CTA.

Assessments of cognitive function

Cognitive function was assessed at 3 months after stroke by two trained neurologists using the MoCA scale. The total score was 0-30 points, and a score < 26 points was defined as PSCI [37]. One point was added to the total score if the patient had less than 12 years of education as MoCA is closely associated with educational level.

Statistical analysis

Statistical analyses were conducted by SPSS version 23.0 (IBM, New York, NY, USA) and GraphPad Prism version 8.0.2 (GraphPad Software, San Diego, CA, USA). Continuous variables were presented as the mean±standard deviation or median (interquartile range [IQR]) and categorical variables were presented as numbers (percentages [%]). We compared all characteristics between the PSCI and nonPSCI subgroups, as well as among the SII and SIRI tertiles. The Chi-square test or Fisher’s exact test was used for categorical variables (such as sex and medical history), and one-way ANOVA, analysis of variance, the Mann-Whitney U test or Kruskal-Wallis test was used for continuous variables (such as age). The association between SII, SIRI and MoCA score was analyzed by Spearman’s correlation. Univariable binary regression analysis was conducted to investigate the association of baseline characteristics with PSCI, and all variables with P < 0.1 were entered into the subsequent multivariable logistic regression model. Odds ratio (OR) or adjusted OR combined with 95% confidence intervals (CIs) demonstrate associations. Subsequently, we evaluated the potential predictive effect of SII on PSCI using ROC curve. All statistical analyses were defined as statistically significant with a two-sided P < 0.05.

Abbreviations

PSCI: post-stroke cognitive impairment; SII: systemic immune-inflammation index; SIRI: systemic inflammation response index; AIS: acute ischemic stroke; MoCA: Montreal Cognitive Assessment; AUC: area under the curve; GBD: Global Burden of Disease; BMI: body mass index; NIHSS: National Institutes of Health Stroke Scale; TOAST: Trial of Org 10172 in Acute Stroke Treatment; TC: total cholesterol; TG: triglyceride; HDL: high-density lipoprotein; LDL: low-density lipoprotein; FPG: fasting plasma glucose; Hcy: homocysteine; UA: uric acid; HbA1c: glycosylated hemoglobin A1; OR: odds ratio; CI: confidence interval; ROC: receiver operating characteristic curve; NLR: neutrophil to lymphocyte ratio; CAD: coronary artery disease; CVD: cardiovascular disease; CSVD: cerebral small vessel disease; BBB: blood-brain barrier; EPVS: enlarged perivascular space; WMH: white matter hyperintensity.

Author Contributions

All authors contributed to the study conception and design. Conceptualization: S.X, S.S and Y.C; methodology: Y.C, H.Z, C.L; software: F.L; validation: S.X, S.S; formal analysis: L.L; investigation: Y.G, C.G, D.S; resources: Y.G; data curation: G.H; writing original draft: Y.C, H.Z, C.L; writing, review and editing: S.X, S.S, Y.C; funding acquisition: D.S. All authors have read and agreed to the published version of the manuscript.

Acknowledgments

We acknowledge all patients and their families who participated in this study.

Conflicts of Interest

The authors declare that they have no conflicts of interest.

Ethical Statement and Consent

This study was approved by the Medical Ethics Committee of the First People’s Hospital of Yancheng (Approval number: 2023-K-199) and was conducted following the Declaration of Helsinki. Written informed consent was obtained from all participants.

Funding

This work was funded by the Science and Technology Bureau of Yancheng (YK2019005 and YK2021026).

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