The Predictive Role of Systemic Inflammation Response Index (SIRI) in the Prognosis of Stroke Patients

Figures & data

Table 1 Baseline Characteristics of the Study Population

Characteristics	SIRI			P value
	<1.6	1.6–3.8	>3.8
Number of patients	817	816	817
Age, years	67.6 ± 15.7	68.0 ± 16.1	68.9 ± 15.2	0.247
Sex, n (%)				<0.001
Female	440 (53.9)	375 (46.0)	354 (43.3)
Male	377 (46.1)	441 (54.0)	463 (56.7)
Ethnicity, n (%)				<0.001
Black	578 (70.7)	630 (77.2)	632 (77.4)
White	100 (12.2)	49 (6.0)	40 (4.9)
Other	139 (17.0)	137 (16.8)	145 (17.7)
Vital signs
Heart rate, beats/minute	78.4 ± 15.2	79.1 ± 14.5	84.2 ± 16.1	<0.001
SBP, mmHg	129.9 ± 17.6	130.5 ± 17.6	127.2 ± 18.3	<0.001
DBP, mmHg	63.3 ± 10.6	64.1 ± 11.7	62.8 ± 11.3	<0.001
MAP, mmHg	83.1 ± 11.1	83.6 ± 11.7	81.7 ± 11.9	<0.001
Respiratory rate, times/minute	18.0 ± 3.3	18.2 ± 3.6	19.4 ± 4.1	<0.001
Temperature, °C	36.8 ± 0.6	36.9 ± 0.6	37.0 ± 0.7	<0.001
SpO2, %	97.6 ± 1.8	97.2 ± 3.1	97.4 ± 2.6	0.140
Laboratory parameters
SIRI, 10^9/L	0.9 ± 0.4	2.6 ± 0.6	10.9 ± 14.2	<0.001
Neutrophil, %	67.9 ± 15.9	81.6 ± 8.0	85.9 ± 8.4	<0.001
Monocyte, %	4.0 ± 2.3	3.9 ± 2.0	4.6 ± 3.6	<0.001
Lymphocyte, %	23.8 ± 12.2	12.5 ± 4.9	7.1 ± 3.4	<0.001
White blood cell counts, 10^9/L	8.9 ± 11.1	11.0 ± 3.4	16.5 ± 13.9	<0.001
Platelet counts, 10^9/L	226.5 ± 103.7	243.9 ± 95.6	260.8 ± 123.1	<0.001
Glucose, mg/dL	138.7 ± 57.1	151.5 ± 65.6	163.8 ± 68.3	0.001
Blood urea nitrogen, mg/dl	22.1 ± 15.9	22.5 ± 16.0	27.3 ± 21.9	<0.001
Anion gap, mg/dl	15.0 ± 3.4	15.3 ± 3.3	16.3 ± 3.9	<0.001
Comorbidities, n (%)
Atrial fibrillation	208 (25.5)	239 (29.3)	251 (30.7)	0.051
CAD	148 (18.1)	147 (18.0)	149 (18.2)	0.993
Liver disease ^$	21 (2.6)	16 (2.0)	26 (3.2)	0.296
Respiratory failure	168 (20.6)	219 (26.8)	297 (36.4)	<0.001
Pneumonia	123 (15.1)	177 (21.7)	253 (31.0)	<0.001
Scoring systems
SOFA	3.4 ± 2.7	3.5 ± 2.6	4.4 ± 3.1	<0.001
SAPSII	34.8 ± 13.3	34.9 ± 13.0	41.0 ± 14.2	<0.001
GCS	12.9 ± 3.2	12.7 ± 3.3	12.3 ± 3.8	0.003
APSIII	40.8 ± 19.7	40.2 ± 19.2	47.8 ± 22.6
Clinical outcomes, n (%)
30-day mortality	141 (17.3)	161 (19.7)	235 (28.8)	<0.001
90-day mortality	173 (21.2)	201 (24.6)	285 (34.9)	<0.001
One-year mortality	219 (26.8)	242 (29.7)	332 (40.6)	<0.001
In-hospital mortality	163 (20.0)	190 (23.3)	271 (33.2)	<0.001
Sepsis	193 (23.6)	232 (28.4)	330 (40.4)	<0.001

Notes: SIRI is calculated using the counts of peripheral venous blood neutrophils (N), monocytes (M), and lymphocytes (L) as follows: SIRI=N*M/L; Data were presented as the mean ± SD and n.

Abbreviations: SIRI, systemic inflammation response index; SBP, systolic blood pressure; DBP, diastolic blood pressure; MAP, mean arterial pressure; SpO2, pulse oximetry-derived oxygen saturation; CAD, coronary artery disease; SOFA, sequential organ failure assessment; SAPS II, simplified acute physiology score II; GCS, Glasgow Coma Scale; APSIII, Antiphospholipid syndrome.

Table 2 Association Between SIRI and Clinical Outcomes of in Critically Ill Patients with Stroke

Clinical Outcomes	Model 1		Model 2		Model 3
	HR (95% CI)	P value	HR (95% CI)	P value	HR (95% CI)	P value
Primary outcome
90-day mortality ^a
Continuous variable	1.01 (1.01, 1.02)	<0.0001	1.01 (1.01, 1.02)	<0.0001	1.01 (1.01, 1.02)	<0.0033
Tertile
<1.6	1.0		1.0		1.0
1.6–3.8	1.21 (0.99, 1.48)	0.0684	1.19 (0.97, 1.46)	0.0948	1.31 (1.04, 1.65)	0 0.0967
>3.8	1.80 (1.49, 2.18)	<0.0001	1.75 (1.45, 2.11)	<0.0001	1.42 (1.13, 1.78)	0.0128
P for trend		<0.0001		<0.0001		0.0238
Secondary outcomes
30-day mortality
Continuous variable	1.01 (1.01, 1.02)	<0.0001	1.01 (1.01, 1.02)	<0.0001	1.01 (1.01, 1.02)	<0.0033
Tertile
<1.6	1.0		1.0		1.0
1.6–3.8	1.19 (0.95, 1.49)	0.1368	1.17 (0.93, 1.47)	0.1721	1.16 (0.92, 1.47)	0.2162
>3.8	1.79 (1.46, 2.21)	<0.0001	1.73 (1.41, 2.14)	<0.0001	1.26 (1.00, 1.59)	0.0361
P for trend		<0.0001		<0.0001		0.0461
One-year mortality ^a
Continuous variable	1.01 (1.01, 1.02)	<0.0001	1.01 (1.01, 1.02)	<0.0001	1.01 (1.00, 1.02)	0.0007
Tertile
<1.6	1.0		1.0		1.0
1.6–3.8	1.15 (0.96, 1.38)	0.1345	1.13 (0.94, 1.36)	0.0387	1.13 (0.93, 1.37)	0.2065
>3.8	1.69 (1.43, 2.01)	<0.0001	1.65 (1.39, 1.96)	<0.0001	1.28 (1.06, 1.54)	0.0108
P for trend		<0.0001		<0.0001		0.0128
In-hospital mortality
Continuous variable	1.01 (1.01, 1.02)	<0.0001	1.01 (1.01, 1.02)	<0.0001	1.01 (1.00, 1.02)	0.0039
Tertile
<1.6	1		1		1
1.6–3.8	1.21 (0.98, 1.50)	0.0700	1.20 (0.97, 1.48)	0.0901	1.13 (0.90, 1.41)	0.0901
>3.8	1.86 (1.53, 2.26)	<0.0001	1.82 (1.50, 2.21)	<0.0001	1.26 (1.02, 1.57)	0.0330
P for trend		<0.0001		<0.0001		0.0379

Notes: ^aCox proportional hazards regression models were used to calculate hazard ratios (HR) with 95% confidence intervals (CI). Model 1 covariates were adjusted for nothing. Model 2 covariates were adjusted for age, sex and ethnicity. Model 3 covariates were adjusted for age, sex, ethnicity, systolic blood pressure, diastolic blood pressure, heart rate, glucose, anion gap, temperature, platelet counts, atrial fibrillation, liver disease, respiratory failure, serum creatinine, hemoglobin GCS, SOFA.

Figure 1 The relationship between systemic inflammatory response index (SIRI) and all-cause mortality. (A) 30-day mortality. (B) 90-day mortality. (C) one year mortality.

Table 3 Association Between SIRI and Clinical Outcomes of Sepsis

Clinical Outcomes	Model 1		Model 2		Model 3
	OR (95% CI)	P value	OR (95% CI)	P value	OR (95% CI)	P value
Continuous variable	1.04 (1.02, 1.05)	<0.0001	1.04 (1.02, 1.05)	<0.0001	1.02 (1.00, 1.03)	0.0085
Tertile
<1.6	1.0		1.0		1.0
1.6–3.8	1.28 (1.03, 1.60)	0.0270	1.32 (1.06, 1.65)	0.0145	1.20 (0.92, 1.57)	0.1822
>3.8	2.19 (1.77, 2.71)	<0.0001	2.26 (1.82, 2.81)	<0.0001	1.45 (1.10, 1.91)	0.0077
P for trend		<0.0001		<0.0001		0.0095

Notes: Logistic regression models were used to calculate odds ratios (OR) with 95% confidence intervals (CI). Model 1 covariates were adjusted for nothing. Model 2 covariates were adjusted for age, sex and ethnicity. Model 3 covariates were adjusted for systolic blood pressure, diastolic blood pressure, system inflammatory response syndrome, serum creatinine, hemoglobin, white blood cell count, platelet count, red cell volume distribution width, atrial fibrillation, coronary artery disease, chronic kidney disease, respiratory failure, pneumonia, GCS and SOFA.

Table 4 Subgroup Analysis of the Associations Between 90-Day All-Cause Mortality and the SIRI^a

	No. of Patients	HR (95% CI) ^b	P for Interaction
Age, years			0.2759
<70	1225	1.02 (1.01, 1.03)
≥71	1225	1.01 (1.00, 1.02)
Gender			0.8323
Male	1281	1.01 (1.01, 1.02)
Female	1169	1.01 (1.01, 1.02)
Ethnicity			0.7819
White	1840	1.01 (1.01, 1.02)
Black	189	1.00 (0.95, 1.06)
Other	421	1.02 (1.00, 1.03)
MAP, mmHg			0.4585
<82	1222	1.01 (1.01, 1.02)
≥83	1222	1.02 (1.01, 1.04)
Heart rate, beats/minute			0.8849
<78	1222	1.02 (1.01, 1.02)
≥79	1223	1.01 (1.00, 1.02)
Respiratory rate, times/minute			0.8322
<18	1221	1.02 (1.01, 1.02)
≥18	1222	1.01 (1.00, 1.02)
Congestive hearts failure			0.2162
Yes	232	1.01 (0.98, 1.04)
No	2218	1.01 (1.01, 1.02)
Atrial fibrillation			0.2627
Yes	698	1.01 (1.00, 1.02)
No	1752	1.02 (1.01, 1.02)
Liver disease			0.7741
Yes	63	1.09 (1.05, 1.13)
No	2387	1.01 (1.01, 1.02)
Coronary artery disease			0.4418
Yes	444	1.01 (1.00, 1.02)
No	2006	1.02 (1.01, 1.02)
Pneumonia			0.1167
Yes	553	1.02 (1.01, 1.03)
No	1897	1.01 (1.01, 1.02)
Anion gap, mmol/l			0.0494
≤14	994	1.01 (1.01, 1.02)
≥15	1447	1.02 (1.00, 1.03)
Glucose, mg/dl			0.0952
≤133	1207	1.03 (1.02, 1.04)
≥134	1241	1.01 (1.00, 1.02)
Serum urea nitrogen, mg/dl			0.1809
≤18	1196	1.02 (1.01, 1.03)
≥19	1253	1.01 (1.00, 1.02)
Potassium, mmol/l			0.8999
≤3.9	1096	1.02 (1.01, 1.02)
≥4.0	1354	1.01 (1.01, 1.02)
Sodium, mmol/l			0.4633
≥138	1011	1.01 (1.01, 1.02)
≥139	1438	1.02 (1.01, 1.02)
APTT, second			0.8038
≤26.6	1193	1.02 (1.01, 1.03)
>26.7	1217	1.01 (1.01, 1.02)
INR			0.0214
≤1.0	578	1.02 (0.99, 1.05)
≥1.1	1836	1.01 (1.01, 1.02)
PT, second			0.6098
≤13.1	1140	1.02 (1.00, 1.04)
≥13.2	1274	1.01 (1.01, 1.02)
SAPSII			0.3413
≤34	1154	1.05 (1.02, 1.08)
≥35	1296	1.01 (1.00, 1.01)
APSIII			0.1427
≤37	1189	1.03 (1.02, 1.05)
≥38	1261	1.01 (1.00, 1.01)

Notes: Cox proportional hazards regression models were used to calculate hazard ratios (HR) with 95% confidence intervals (CI). ^aCox proportional hazards regression models were used to calculate hazard ratios (HR) with 95% confidence intervals (CI). ^bcovariates were adjusted for age, sex and ethnicity.

Table 5 Receiver Operating Curve (ROC) for Prediction in Stroke Patients

	ROC Area (AUC)	95% CI Low	95% CI Upp
NLR	0.5349	0.5102	0.5598
PLR	0.5628	0.5378	0.5879
LMR	0.5579	0.5332	0.5825
RDW	0.5865	0.5618	0.6113
SIRI	0.6216	0.5979	0.6453

Abbreviations: AUC, area under the curve; CI, confidence interval; NLR, neutrophil-to-lymphocyte ratio; PLR, platelet-to-lymphocyte ratio; LMR, lymphocyte to monocyte ratio; RDW, red blood cell distribution width; SIRI, systemic inflammation response index.

Figure 2 Receiver operating curve (ROC) for prediction in stroke patients using systemic inflammatory response index (SIRI). (AUC: SIRI: 0.622; RDW: 0.587; PLR:0.563; LMR: 0.558; NLR:0.535, separately).

Figure 3 Pearson’s correlation test to analyze the relationship between systemic inflammatory response index (SIRI) and National Institute of Health stroke scale (NIHSS). (R² = 0.3404, p < 0.001).