Systemic Immune-Inflammation Index Predicts 3-Month Functional Outcome in Acute Ischemic Stroke Patients Treated with Intravenous Thrombolysis

Figures & data

Figure 1 Flow chart for patients’ selection.

Table 1 Baseline Clinical Characteristics of AIS Patients and Healthy Controls

Variables	Before Propensity Score Matching				After Propensity Score Matching
	AIS (n = 216)		HC (n = 875)	p	AIS (n = 83)	HC (n = 83)	p
Age (years)	68.5 (59.25–76)		39 (33–47)	< 0.001	59.24 ± 11.54	58.22 ± 13.24	0.596
Sex (male, n%)	136 (63.0)		610 (69.7)	0.056	54 (65.1)	60 (72.3)	0.315
Current smoking (n%)	60 (28.6)		NA		28 (31.5)	NA
Hypertension (n%)	131 (61.0)		45 (5.1)	< 0.001	24 (29.0)	23 (27.8)	0.863
Diabetes (n%)	46 (21.3)		5 (0.6)	< 0.001	6 (7.2)	4 (4.8)	0.514
Hyperlipidemia (n%)	28 (13.0)		57 (6.5)	0.002	13 (15.7)	14 (16.9)	0.833
AF (n%)	55 (25.5)		NA		17 (20.5)	NA
CAD (n%)	9 (4.0)		NA		3 (3.6)	NA
Prior stroke, n (%)	19 (8.8)		NA		2 (2.4)	NA
Baseline NIHSS score	7 (4–11)		NA		6 (4–10)	NA
Stroke subtype (n%)			NA			NA
LAA	88 (41.9)				29 (35.0)
SAO	29 (13.8)				15 (18.1)
CE	75 (35.7)				23 (27.7)
Others	24 (11.4)				16 (19.3)
Neutrophil (10^9/L)	5.00 (3.60–6.20)		3.26 (2.61–4.05)	< 0.001	4.90 (3.60–6.10)	3.29 (2.58–4.02)	< 0.001
Lymphocyte (10^9/L)	1.50 (1.20–2.00)		2.24 (1.85–2.64)	< 0.001	1.60 (1.30–2.00)	2.09 (1.68–2.48)	< 0.001
Platelet (10^9/L)	194.00 (154.50–229.25)		231.00 (201.00–265.00)	< 0.001	200.69 ± 55.15	218.41 ± 49.21	0.012
SII (10^9/L)	629.86 (393.90–928.66)		331.91 (254.20–454.87)	< 0.001	644.29 (363.79–942.29)	330.18 (249.47–489.29)	< 0.001

Abbreviations: AIS, acute ischemic stroke; HC, healthy control; SII, systemic immune-inflammation index; NIHSS, national institute of health stroke scale; AF, atrial fibrillation; CAD, coronary artery disease; LAA, large artery atherosclerosis; SAO, small artery occlusion; CE, cardio-embolism.

Table 2 Comparisons of Baseline Characteristics and Outcomes Between SII Groups

Variable	SII ≤ 545.14 (n = 87)	SII > 545.14 (n = 129)	p
Age (years)	69 (59–75)	67 (59.5–78)	0.819
Sex (male, n%)	58 (66.7)	78 (60.5)	0.355
Current smoking (n%)	26 (29.9)	29 (22.5)	0.221
Hypertension (n%)	56 (64.4)	75 (58.1)	0.358
Diabetes (n%)	20 (23.0)	26 (20.2)	0.618
Hyperlipidemia (n%)	8 (9.2)	20 (15.5)	0.176
AF (n%)	26 (29.9)	29 (22.5)	0.221
CAD (n%)	3 (3.4)	6 (4.7)	0.664
Prior stroke (n%)	5 (5.7)	14 (10.9)	0.194
Baseline NIHSS score	5 (4–9)	9 (5.5–13.5)	< 0.001
Stroke subtype (n%)			0.607
LAA	34 (39.1)	54 (41.9)
SAO	15 (17.2)	14 (10.9)
CE	29 (33.3)	46 (35.7)
Others	9 (10.3)	15 (11.6)
Neutrophil (10^9/L)	3.60 (3.00–4.50)	5.90 (4.95–7.10)	< 0.001
Lymphocyte (10^9/L)	1.80 (1.40–2.30)	1.40 (1.10–1.70)	< 0.001
Platelet (10^9/L)	196.84 ± 57.22	188.47 ± 59.55	< 0.001
SII (10^9/L)	357.78 (279.82–446.18)	884.58 (682.52–1036.21)	< 0.001
Favorable outcomes at 90 days (mRS ≤2) (n%)	76 (87.4)	76 (58.9)	< 0.001

Abbreviations: SII, systemic immune-inflammation index; NIHSS, national institute of health stroke scale; AF, atrial fibrillation; CAD, coronary artery disease; LAA, large artery atherosclerosis; SAO, small artery occlusion; CE, cardio-embolism; mRS, modified Rankin Scale.

Figure 2 Receiver operator characteristic curves for the prediction of 3-month poor outcome using systemic immune-inflammation index (SII).

Figure 3 The association between SII and NIHSS. (A) A positive correlation of SII with NIHSS scores (rs = 0.305, p < 0.001). The red solid straight line was produced by linear regression while the black dotted line represented curve fitting by third order polynomial (cubic). (B) Patients with NIHSS > 10 (n = 60) had a significant increase in SII compared to those with NIHSS ≤ 10 (n = 156) (p = 0.001).

Abbreviations: SII, systemic immune-inflammation index; NIHSS, National Institute of Health stroke scale.

Table 3 Univariate and Multivariate Logistic Regression Analysis for 3-month Poor Outcome

Variables	Univariate Analysis		Model 1*		Model 2^†
	OR (95% CI)	p	OR (95% CI)	p	OR (95% CI)	p
Characteristics
Age (years)	1.061 (1.031–1.092)	< 0.001	1.042 (1.007–1.078)	0.019	1.037 (1.001–1.075)	0.045
Sex (male, n%)	0.805 (0.442–1.466)	0.479
Current smoking	0.173 (0.065–0.458)	< 0.001	0.396 (0.135–1.163)	0.092	0.387 (0.131–1.141)	0.085
Hypertension	1.644 (0.885–3.051)	0.115			2.064 (0.922–4.623)	0.078
Diabetes	1.050 (0.517–2.134)	0.893			1.304 (0.539–3.155)	0.556
Hyperlipidemia	1.962 (0.869–4.426)	0.105
AF	2.104 (1.107–3.999)	0.023	1.635 (0.719–3.719)	0.241	1.777 (0.764–4.135)	0.182
CAD	1.960 (0.509–7.550)	0.328
Prior stroke	3.736 (1.425−9.792)	0.007	1.604 (0.483–5.332)	0.440	1.291 (0.379–4.392)	0.683
Baseline NIHSS score	1.214 (1.137–1.295)	< 0.001	1.154 (1.079–1.235)	< 0.001	1.170 (1.091–1.255)	< 0.001
Stroke subtype
LAA	0.906 (0.499–1.645)	0.745
SAO	NA
CE	2.535 (1.386–4.637)	0.003
Others	0.975 (0.384–2.479)	0.958
High SII	4.818 (2.338–9.929)	< 0.001	3.925 (1.694–9.096)	0.001	3.953 (1.702–9.179)	0.001

Notes: *Model 1: adjusted for age, current smoking, AF, prior stroke and baseline NIHSS score. ^†Model 2: Model 1 + hypertension and diabetes.

Abbreviations: SII, systemic immune-inflammation index; NIHSS, national institute of health stroke scale; AF, atrial fibrillation; CAD, coronary artery disease; LAA, large artery atherosclerosis; SAO, small artery occlusion; CE, cardio-embolism.

Table 4 Reclassification and Discrimination Statistics for Poor Functional Outcomes by SII at 3 Months

	C-Statistics		Continuous NRI, %		IDI, %
	Estimate (95% CI)	p value	Estimate (95% CI)	p value	Estimate (95% CI)	p value
Conventional model	0.814 (0.755–0.863)		Reference		Reference
Conventional model + SII	0.825 (0.768–0.874)	0.487	39.3 (10.6–68.0)	0.007	3.70 (0.98–6.42)	0.008

Note: The conventional model contained stroke severity by baseline NIHSS score and age.

Abbreviations: SII, systemic immune-inflammation index; SII, net reclassification improvement; IDI, integrated discrimination improvement; NIHSS, national institute of health stroke scale.

Figure 4 mRS distribution at 3 months for high SII group vs low SII group. mRS, modified Rankin Scale; SII, systemic immune-inflammation index.