Dynamics in perioperative neutrophil-to-lymphocyte*platelet ratio as a predictor of early acute kidney injury following cardiovascular surgery

Figures & data

Table 1. Demographic and perioperative factors of CSA-AKI (n = 2449).

Variables	AKI	Non-AKI	Stat. value	p-Value
Age (year)	59.5 ± 11.0	56.0 ± 13.5	−6.567	<0.001^†
Gender (male %)	576 (68.7)	873 (54.2)	48. 272	<0.001^#
BMI (kg/m²)	24.4 ± 3.8	23.4 ± 3.4	−6.386	<0.001^†
Hypertension (%)	410 (48.9)	550 (34.1)	50.565	<0.001^#
Diabetes (%)	107 (12.8)	161 (10.0)	4.355	0.037^#
Unstable angina pectoris (%)	37 (4.4)	74 (4.6)	N/A	0.919*
Myocardial infarction (%)	12 (1.4)	13 (0.8)	N/A	0.202*
Cardiac surgery history (%)	52 (6.2)	56 (3.5)	N/A	0.002*
NYHA grade ≥ 3 (%)	666 (78.5)	1002 (62.2)	75.761	<0.001^#
Coronary Arteriography (yes %)	551 (65.8)	942 (58.5)	12.272	<0.001^#
LEVF (%)	60.1 ± 8.9	62.3 ± 7.9	6.320	<0.001^†
PAH (mmHg)	41.6 ± 13.5	41.1 ± 14.7	−0.751	0.453^†
BUN (mmol/L)	7.3 ± 5.8	6.3 ± 3.1	−5.566	<0.001^†
SCr (µmol/L)	90.6 ± 48.8	82.7 ± 61.8	−3.190	0.001^†
eGFR (ml/min/1.73m²)	80.3 ± 23.3	86.4 ± 19.4	6.908	<0.001^†
SUA (µmol/L)	394.2 ± 121.1	354.1 ± 105.7	−8.477	<0.001^†
Proteinuria (yes %)	80 (9.5)	79 (4.9)	19.572	<0.001^#
Random blood sugar (mmol/L)	5.0[4.6, 5.7]	4.9[4.6, 5.5]	N/A	0.002^‡
Albumin (g/L)	40.2 ± 4.5	40.6 ± 4.3	2.516	0.012^†
Surgery type			84.300	<0.001^#
Valve	463 (55.3)	793 (49.2)
CABG	73 (8.7)	259 (16.1)
Aorta	124 (14.8)	146 (9.1)
Valve + CABG	42 (5.0)	32 (2.0)
Valve + large vessels	40 (4.8)	59 (3.7)
Others	96 (11.5)	322 (20.0)
CPB (yes %)	740 (88.3)	1029 (63.9)	164.064	<0.001^#
ACCT (min)	68.8 ± 39.7	64.0 ± 55.2	−2.021	0.043^†
Ultrafiltration volume (L)	2.5[2.0, 3.3]	2.0[1.5, 2.7]	N/A	<0.001^‡
Blood transfusion (yes, %)	222 (26.5)	127 (7.9)	156.207	<0.001^#
Plasma (ml)	400[400, 600]	400[200, 400]	N/A	<0.001^‡
Euro score	3.9 ± 2.4	3.5 ± 2.2	−4.338	<0.001^†
APACHE II score	8.2 ± 4.2	6.5 ± 3.4	−10.914	<0.001^†

^†Refers to Student’s t test (for continuous variables which were normally distributed).

^#Refers to Pearson test (for binary and unordered categorical variables).

*Refers to Fisher’s exact test (for categorical variables when sample sizes are small).

^‡Refers to Wilcoxon test (for continuous variables which were non-normally distributed).

ACCT: aortic cross-clamp time; AKI: acute kidney injury; aOR: adjusted odds ratio; CABG: coronary artery bypass grafting; CI: confidence interval; CPB: cardiac pulmonary bypass; CSA-AKI: cardiac surgery-associated acute kidney injury; eGFR: estimated glomerular filtration rate; LVEF: left ventricular ejection fractions; NYHA: New York heart association; PAH: pulmonary arterial hypertension; SCr: serum creatinine; SUA: serum uric acid.

Table 2. Distribution of peripheral blood cell counts and NLPR in AKI and non-AKI patients (n = 2449).

Blood cell counts	AKI	Non-AKI	Stat. value	p-Value	aOR (95% CI)^c	p-Value
Pre-surgery (within 24 h of admission)
Leukocyte (10^9/L)	6.3 ± 2.5	6.1 ± 1.9	−2.588	0.009^†	1.03 (0.99–1.08)	0.112
Neutrophil (10^9/L)	3.9 ± 2.4	3.5 ± 1.6	−4.018	<0.001^†	1.07 (1.02–1.12)	<0.001
Lymphocyte (10^9/L)	1.7 ± 0.6	1.9 ± 0.7	4.926	<0.001^†	0.74 (0.64–0.85)	<0.001
Platelet (10^9/L)	182.2 ± 59.6	196.4 ± 60.9	5.542	<0.001^†	0.99 (0.99–1.00)	<0.001
NLPR	1.1[0.8, 1.8]	0.9[0.7, 1.4]	N/A	<0.001^‡	1.15 (1.09–1.22)	<0.001
Post-surgery (within 1 h of arrival in ICU)
Leukocyte (10^9/L)	12.7 ± 3.8	12.2 ± 3.5	−3.382	<0.001^†	1.05 (1.03–1.08)	<0.001
Neutrophil (10^9/L)	10.9 ± 3.5	10.5 ± 3.3	−3.046	0.002^†	1.05 (1.03–1.08)	<0.001
Lymphocyte (10^9/L)	0.8 ± 0.4	0.8 ± 0.4	1.200	0.231^†	0.88 (0.91–1.09)	0.232
Platelet (10^9/L)	137.0 ± 55.0	150.7 ± 55.3	5.800	<0.001^†	0.99 (0.99–1.00)	<0.001
NLPR	12.4[7.5, 20.0]	10.6[6.4, 16.7]	N/A	<0.001^‡	1.02 (1.02–1.03)	<0.001

^aOR was adjusted by age, gender, and body mass index.

^†Refers to Student’s t test (for continuous variables which were normally distributed).

^‡Refers to Wilcoxon test (for continuous variables which were non-normally distributed).

AKI: acute kidney injury; aOR: adjusted odds ratio; ICU: intensive care unit；NLPR: neutrophil-to-platelet*lymphocyte ratio.

Figure 1. Dose-response relationship of CSA-AKI and peripheral blood cell counts and NLPR.

Table 3. Perioperative NLPR levels and their association with CSA-AKI (n = 2449).

	Total	AKI (%)	aOR (95% CI)^a	p-Value
NLPR (pre-surgery)
≤0.49	236	69 (29.2)	1.09 (0.78–1.52)	0.932
0.50–0.99	1005	291 (29.0)	Ref	–
1.00–1.99	843	296 (35.1)	1.23 (1.00–1.51)	0.054
2.00–2.99	200	95 (47.5)	1.80 (1.30–2.49)	<0.001
≥3.00	165	87 (52.7)	2.61 (1.85–3.69)	<0.001
NLPR (post-surgery)
≤4.90	346	97 (28.0)	0.78 (0.58–1.05)	0.107
5.00–9.99	727	230 (31.6)	Ref	–
10.00–19.99	889	301 (33.9)	1.13 (0.91–1.41)	0.278
20.00–29.99	290	119 (41.0)	1.69 (1.26–2.27)	0.001
≥30.00	197	91 (46.2)	2.09 (1.49–2.93)	<0.001

^aOR was adjusted by age, gender, and body mass index.

AKI: acute kidney injury; aOR: adjusted odds ratio; NLPR: neutrophil to platelet*lymphocyte ratio.

Table 4. Antibiotic treatment and the risk of CSA-AKI in high NLPR groups (n = 365).

Antibiotic use	Total		NLPR (2.00–2.99)		NLPR (≥3.00)
	AKI	aOR	AKI	aOR	AKI	aOR
	(%)	(95% CI)^a	(%)	(95% CI)^a	(%)	(95% CI)^a
Yes	27	0.44	10	0.39	17	0.44
	(32.9)	(0.26–0.76)	(29.4)	(0.16–0.95)	(35.4)	(0.21–0.91)
No	155	Ref	85	Ref	70	Ref
	(54.8)		(51.2)		(59.8)

^aOR was adjusted by age, gender, and body mass index.

AKI: acute kidney injury; aOR: adjusted odds ratio; NLPR: neutrophil to platelet*lymphocyte ratio.

Figure 2. Prediction model of CSA-AKI through the generalized estimating equation (GEE). (3A: the optimal NLPR cutoff was set at 1.3; 3B: model 1 only enrolled the NLPR values in two-time points, model2 was model 1 plus demographic factors; model 3 was model 2 plus preoperative factors, model 4 was model 3 plus intra-/postoperative factor; 3C: comparison between the model with and without NLPR).