Neutrophil Percentage as a Potential Biomarker of Acute Kidney Injury Risk and Short-Term Prognosis in Patients with Acute Myocardial Infarction in the Elderly

Figures & data

Figure 1 Study flow chart.

Abbreviations: AMI, acute myocardial infarction; PCI, percutaneous coronary intervention; CABG, coronary artery bypass grafting; IABP, intra-aortic balloon pump; AKI, acute kidney injury.

Table 1 Baseline Information of Enrolled AKI Patients and Participants

Characteristics	overall	Non-AKI (n=2674)	AKI (n=327)	P value
Age, years	64.38±13.74	63.87±13.63	68.54±13.92	<0.001
Male, n (%)	2227(74.2)	2015(75.4)	212(64.8)	<0.001
Body mass index, kg/m^2	24.25±3.68	24.32±3.69	23.70±3.58	0.003
Hypertension, n (%)	1985(66.1)	1733(64.8)	252(77.1)	<0.001
Diabetes, n (%)	961(32.0)	828(31.0)	133(40.7)	<0.001
Current or former smoker, n (%)	1449(48.3)	1319(49.3)	130(39.8)	0.001
Alcohol consumption, n (%)	341(11.4)	315(11.8)	26(8.0)	0.039
STEMI, n (%)	1852(61.7)	1647(61.6)	205(62.7)	0.700
NSTEMI, n (%)	1149(38.3)	1027(38.4)	122(37.3)	0.700
LVEF, %	51.00±9.29	51.22±9.20	49.18±9.82	<0.001
Killip class III or Ⅳ, n (%)	324(10.8)	247(9.2)	77(23.5)	<0.001
SBP, mm/Hg	131.27±24.20	131.33±23.91	130.83±26.49	0.726
DBP, mm/Hg	79.17±15.93	79.26±15.68	78.42±17.80	0.366
Heart rate, bpm	80.21±16.07	79.60±15.54	85.21±19.20	<0.001
WBC, 10^9/L	9.18(7.22–11.76)	9.14(7.19–11.70)	9.35(7.45–12.09)	0.188
Neutrophil percentage, %	73.63±11.82	73.22±11.83	76.65±11.43	<0.001
Neutrophils, 10^9/L	6.67(4.79–9.13)	6.58(4.74–9.06)	7.27(5.36–9.77)	0.003
Hemoglobin, g/L	138.40±20.16	139.38±19.44	130.40±23.87	<0.001
TNI, ng/mL	4.13(0.83–17.80)	4.39(0.82–18.14)	2.71(0.85–11.60)	0.033
Serum creatinine, μmol/L	73.70(61.80–90.50)	73.70(62.20–89.60)	74.00(55.70–99.50)	0.730

Abbreviations: AKI, acute kidney injury; STEMI, ST segment elevation myocardial infarction; NSTEMI, non-ST segment elevation myocardial infarction; LVEF, left ventricular ejection fraction; SBP, systolic blood pressure; DBP, diastolic blood pressure; WBC, white blood cell; TNI, cardiac troponin I.

Figure 2 Neutrophil percentage levels in different groups and the relation of neutrophil percentage with the risk of AKI in a restricted cubic splines model. (A) The violin plot reflects the distribution and probability density of neutrophil percentage levels between the two groups, with dotted lines representing the 25th, 50th, and 75th percentiles. ***P <0.001. (B) The relation of neutrophil percentage with the risk of AKI on a continuous scale. X-axis represents neutrophil percentage. Y-axis represents the probability of AKI. Dashed lines indicate 95% CI. From left to right, the triangles indicate the 25th, 50th, and 75th percentile. (C) The relation between neutrophil percentage and the risk of AKI by restricted cubic splines. The odds ratio is indicated by the solid blue line, and the 95% CI is represented by the shaded regions derived from the three-node restricted cubic spline regression. The horizontal reference line represented by a dashed line indicates a odds ratio of 1.0, and the vertical reference line is the corresponding neutrophil percentage at this time.

Abbreviations: OR, odds ratios; CI, confidence intervals.

Table 2 Medication and Procedural Characteristics of Enrolled AKI Patients and Participants

Characteristics	overall	Non-AKI (n=2674)	AKI (n=327)	P value
Medication before procedures, n (%)
Aspirin	2919(97.3)	2605(97.4)	314(96.0)	0.144
Clopidogrel	851(28.4)	741(27.7)	110(33.6)	0.025
Ticagrelor	2125(70.8)	1910(71.4)	215(65.7)	0.033
ACEI/ARB	1918(63.9)	1709(63.9)	209(63.9)	0.999
β-blocker	1925(64.1)	1712(64.0)	213(65.1)	0.692
Statins	2830(94.3)	2533(94.7)	297(90.8)	0.004
Tirofiban hydrochloride	1503(50.1)	1338(50.0)	165(50.5)	0.886
Procedural characteristics, n (%)
Contrast volume >100 mL	452(15.1)	407(15.2)	45(13.8)	0.486
Contrast exposure time >60 min	593(19.8)	527(19.7)	66(20.2)	0.839
Number of stents with each vessel
Left main coronary artery				0.013
0	2979(99.3)	2658(99.4)	321(98.2)
≥1	22(0.7)	16(0.6)	6(1.8)
Left anterior descending artery				0.075
0	1653(55.1)	1488(55.6)	165(50.5)
≥1	1348(44.9)	1186(44.4)	162(49.5)
Left circumflex artery				0.928
0	2537(84.5)	2260(84.5)	277(84.7)
≥1	464(15.5)	414(15.5)	50(15.3)
Right coronary artery				0.094
0	2158(71.9)	1910(71.4)	248(75.8)
≥1	843(28.1)	764(28.6)	79(24.2)

Abbreviation: ACEI/ARB, angiotensin-converting enzyme inhibitors/angiotensin receptor blockers.

Table 3 Multivariable Logistic Regression Analysis of Risk of AKI in Entire Population

Characteristics	Multivariable Analysis (Model1)		Multivariable Analysis (Model2)		Multivariable Analysis (Model3)
	OR (95% CI)	P	OR (95% CI)	P	OR (95% CI)	P
Age	1.022(1.012–1.031)	<0.001	1.007(0.996–1.018)	0.219	1.006(0.995–1.017)	0.272
Male	0.720(0.556–0.932)	0.013	0.962(0.697–1.328)	0.816	0.945(0.684–1.307)	0.734
Body mass index			0.986(0.953–1.021)	0.428	0.986(0.952–1.021)	0.417
Hypertension			1.640(1.234–2.181)	0.001	1.646(1.237–2.189)	0.001
Diabetes			1.314(1.024–1.687)	0.032	1.300(1.012–1.671)	0.040
Current or former smoker			1.034(0.763–1.403)	0.827	1.012(0.745–1.375)	0.939
Alcohol consumption			0.782(0.500–1.221)	0.279	0.774(0.495–1.212)	0.263
LVEF			0.994(0.982–1.007)	0.401	0.995(0.983–1.008)	0.488
Killip class III or IV			2.042(1.493–2.793)	<0.001	2.117(1.543–2.906)	<0.001
Heart rate			1.014(1.007–1.021)	<0.001	1.014(1.007–1.021)	<0.001
Neutrophil percentage	1.026(1.015–1.037)	<0.001	1.021(1.010–1.033)	<0.001	1.021(1.010–1.033)	<0.001
Hemoglobin			0.987(0.981–0.994)	<0.001	0.988(0.981–0.995)	0.001
TNI			0.992(0.985–0.999)	0.026	0.993(0.985–1.000)	0.042
Medication before procedures
Clopidogrel					2.138(0.598–7.643)	0.242
Ticagrelor					2.108(0.594–7.479)	0.249
Statins					0.597(0.380–0.938)	0.025
Number of stents with left main coronary artery≥1					2.667(0.961–7.403)	0.060

Notes: Model 1 adjusted for age and gender; model 2 adjusted for covariates in model 1 plus body mass index, hypertension, diabetes, current or former smoker, alcohol consumption, LVEF, Killip class III or IV, heart rate, neutrophil percentage, neutrophils, hemoglobin, and TNI; model 3 adjusted for covariates in model 2 plus use of clopidogrel, use of ticagrelor, use of statins, and left main coronary artery stent implantation.

Abbreviations: OR, odds ratios; CI, confidence intervals.

Table 4 Neutrophil Percentage Level and Risk of AKI in Entire Population

	Neutrophil Percentage (Range)	Odds Ratio (95% CI) and P value
		Unadjusted	Model1	Model2	Model3
Neutrophil percentage (per 1 SD)	(24.20–98.81)	1.367(1.207–1.549)	1.350(1.189–1.532)	1.294(1.091–1.534)	1.290(1.087–1.531)
		<0.001	<0.001	0.003	0.004
Neutrophil percentage quartiles
Q1	59.30(24.20–65.50)	1	1	1	1
		Reference	Reference	Reference	Reference
Q2	70.60(65.51–75.01)	1.344(0.931–1.939)	1.291(0.892–1.867)	1.246(0.850–1.825)	1.234(0.842–1.809)
		0.114	0.176	0.259	0.281
Q3	78.91(75.02–83.00)	1.723(1.212–2.450)	1.638(1.148–2.337)	1.538(1.040–2.276)	1.526(1.030–2.260)
		0.002	0.006	0.031	0.035
Q4	87.00(83.01–98.81)	2.178(1.549–3.064)	2.114(1.499–2.981)	1.917(1.231–2.984)	1.903(1.220–2.968)
		<0.001	<0.001	0.004	0.005
P for trend		<0.001	<0.001	0.003	0.003

Abbreviation: SD, standard deviation.

Figure 3 Survival analyses according to neutrophil percentage quartiles and the incidence of AKI. (A) Short-term survival rate according to neutrophil percentage quartiles (Q1 versus Q2 and Q3 and Q4); (B) Survival rate between AKI group and non-AKI group.

Figure 4 Correlation of variables in AMI patients. The diagonals show the distribution; the lower left part shows a two-variable scatter diagram with fitting lines; the upper right shows the correlation coefficient and significance level, and the numbers represent the correlation coefficient. ***P < 0.001.

Abbreviations: BMI, body mass index; SBP, systolic blood pressure; HR, heart rate; NEUT%, neutrophil percentage; Hb, hemoglobin; LVEF, left ventricular ejection fraction.