Systemic Immune-Inflammation Index Predicts Prolonged Mechanical Ventilation and Intensive Care Unit Stay After off-Pump Coronary Artery Bypass Graft Surgery: A Single-Center Retrospective Study

Figures & data

Figure 1 Study flow diagram.

Table 1 Patients Characteristics

Variables	SII <878.057 (n = 308)	SII ≥878.057 (n = 63)	p-value
Age, years (Mean ± SD)	58.94 ± 7.87	60.63 ± 6.64	0.111
Sex
Male	259 (84.1%)	51 (81%)	0.670
Female	49 (15.9%)	12 (19%)
Body Mass Index, kg/m^2 (Median [min-max])	25.59 (13.71–40.27)	24.77 (20.00–35.00)	0.396
Hypertension (%)	197 (64%)	43 (68.3%)	0.565
Diabetes Mellitus (%)	104 (33.8%)	27 (42.9%)	0.193
Dyslipidemia (%)	90 (29.2%)	18 (28.6%)	1.000
Chronic Obstructive Pulmonary Disorder (%)	4 (1.3%)	3 (4.8%)	0.183
Smoking History (%)	165 (53.6%)	39 (61.9%)	0.267
Active Smoker	9 (2.9%)	5 (7.9%)	0.123
Recent MI (%)	109 (35.4%)	16 (25.4%)	0.145
Family History of CAD (%)	50 (16.2%)	9 (14.3%)	0.844
Preoperative Ejection Fraction, % (Median [min-max])	57 (15–86)	55 (21–80)	0.363
LM Disease (%)	92 (29.9%)	25 (39.7%)	0.138
EuroSCORE II (Median [min-max])	1.02 (0.50–9.79)	1.19 (0.55–5.95)	0.030*

Note: *Statistical significance (p < 0.05) is marked with.

Abbreviations: CAD, coronary artery disease; LM, left main; MI, myocardial infarct; SD, standard deviation; SII, systemic immune-inflammation index.

Table 2 Laboratory Parameters

Variables	SII <878.057 (n = 308)	SII ≥878.057 (n = 63)	p-value
Neutrophil Count (Median [min-max])	57.25 (30.00–76.80)	69.7 (31.20–86.10)	<0.001*
Lymphocyte Count (Median [min-max])	29.75 (8.80–57.10)	18.00 (2.40–29.30)	<0.001*
Platelet Count (Mean ± SD)	242.16 ± 56.75	318.54 ± 90.04	<0.001*
NLR (Median [min-max])	1.92 (0.53–5.09)	3.85 (1.79–34.04)	<0.001*
SII (Median [min-max])	466.059 (119.790–877.272)	1131.330 (878.718–8788.138)	<0.001*

Note: *Statistical significance (p < 0.05) is marked with.

Abbreviations: NLR, neutrophil-to-lymphocyte ratio; SD, standard deviation; SII, systemic immune-inflammation index.

Table 3 Procedural Data

Variables	SII <878.057 (n = 308)	SII ≥878.057 (n = 63)	p-value
Duration of surgery, minutes (Median [min-max])	270 (97–646)	270 (90–450)	0.306
Number of grafts (%)
1	7 (2.3%)	0 (0%)	0.062
2	89 (28.9%)	11 (17.5%)
3	205 (66.6%)	52 (82.5%)
4	7 (2.3%)	0 (0%)
IABP (%)	26 (8.4%)	8 (12.7%)	0.408
Blood Transfusion (%)	38 (12.3%)	9 (14.3%)	0.829
PRC	33 (10.7%)	8 (12.7%)	0.813
FFP	9 (2.9%)	2 (3.2%)	1.000
TC	5 (1.6%)	1 (1.6%)	1.000

Abbreviations: FFP, fresh frozen plasma; IABP, intra-aortic balloon pump; PRC, packed red cell; TC, thrombocyte concentrate.

Table 4 Perioperative Outcomes

Variables	SII <878.057 (n = 308)	SII ≥878.057 (n = 63)	p-value
VIS (Median [min-max])	2.5 (0.0–508.0)	3.0 (0.0–508.0)	0.407
PoAF (%)	19 (6.2%)	3 (4.8%)	0.890
Stroke (%)	2 (0.6%)	1 (1.6%)	1.000
MI (%)	8 (2.6%)	2 (3.2%)	1.000
DO-MV, hours (Median [min-max])	10 (3–229)	12 (4–240)	0.047*
LOS-ICU, hours (Median [min-max])	22 (2–326)	23 (8–312)	0.049*
LOS-H, days (Median [min-max])	7 (1–55)	7 (1–36)	0.035*
Mortality (%)	12 (3.9%)	3 (4.8%)	1.000

Note: *Statistical significance (p < 0.05) is marked with.

Abbreviations: DO-MV, duration of mechanical ventilation; LOS-H, length of hospital stay; LOS-ICU, length of intensive care unit stay; MI, myocardial infarct; PoAF, postoperative atrial fibrillation; VIS, vasoactive-inotropic score.

Table 5 Analysis of High SII Values in Predicting Poor Perioperative Outcomes

Variables	RR	95% CI		p-value
		Lower	Upper
Prolonged Mechanical Ventilation (DO-MV >24 hours)	1.141	1.001	1.301	0.019*
Prolonged ICU Stay (LOS-ICU > 48 hours)	1.218	1.021	1.452	0.011*
Prolonged Hospital Stay (LOS-H > 7 days)	1.173	0.920	1.496	0.212

Note: *Statistical significance (p < 0.05) is marked with.

Abbreviations: CI, confidence interval; DO-MV, duration of mechanical ventilation; ICU, intensive care unit; LOS-H, length of hospital stay; LOS-ICU, length of intensive care unit stay; RR, relative risk.

Table 6 Correlation Between SII and Perioperative Outcomes

Variables	SII
	p-value	R-value
VIS	0.069	0.095
DO-MV, hours	0.402	0.044
LOS-ICU, hours	0.200	0.067
LOS-H, days	0.010*	0.133*

Notes: *Statistical significance (p < 0.05) is marked with.

Abbreviations: DO-MV, duration of mechanical ventilation; LOS-H, length of hospital stay; LOS-ICU, length of intensive care unit stay; SII, systemic immune-inflammation index; VIS, vasoactive-inotropic score.

Figure 2 Receiver operating characteristic curve (ROC) for prediction of mechanical ventilation duration based on SII. AUC, area under curve; SII, systemic immune-inflammation index. The highest area under the curve of 0.658 (p = 0.001) for systemic immune-inflammation index, with its respective cutoff value of 600.897 x 10³/mm³.

Data Sharing Statement

Individual deidentified participant data from this study will be made available upon request after publication and will be available for 36 months following article publication. Researchers need to state their aims of analysis and provide a methodologically sound proposal directed towards the corresponding author.