Serum chemokine IL-8 acts as a biomarker for identifying COVID-19-associated persistent severe acute kidney injury

Figures & data

Figure 1. Selection of patients included in this study.

Table 1. Baseline characteristics of the COVID-19 patients.

Variables	Not persistent severe AKI (N = 88)	Persistent severe AKI (N = 27)	P-value
Male (%)	48 (54.5%)	13 (48.1%)	0.562
Age (years)	73.02 ± 15.35	73.63 ± 12.57	0.852
Septic shock (%)	30 (34.1%)	19 (70.4%)	<0.001
Laboratory parameters
WBC (10^9/L) ^#	8.97(6.64,11.92)	10.48(6.04,13.24)	0.682
CRP (mg/L) ^#	102.5(48.4,194.2)	167.5(108.7,250.0)	0.002
IL-6 (pg/mL) ^#	62.7(22.9,261.5)	215.6(94.2,894.6)	0.001
Urea (mmol/L) ^#	13.7 (8.4,23.0)	15.8 (9.7,34.5)	0.088
Scr (μmoI/L) ^#	123.5 (95.5, 200.3)	196.0 (122.0,288.0)	0.008
Total protein (g/L) ^#	56.9 (51.2,61.3)	58.4 (50.8,60.6)	0.963
Albumin (g/L) ^#	30.6 (27.7,33.2)	32.1 (29.2,36.6)	0.164
D-Dimer (μg/L) ^#	2199.5 (1293.0,4596.0)	2193.0 (1568.0,4217.0)	0.707
Clinical symptom
PaO2, mmHg^#	78.9 (53.1,93.9)	71.9 (41.5, 82.0)	0.096
SpO2, %^#	95.8 (87.8, 97.8)	91.3 (80.0,97.1)	0.080
P/F Ratio^#	211.6 (149.3,290.6)	256.8 (190.5, 319.2)	0.139
SOFA score^#	6.5(5.0,10.0)	10.0(6.0,13.0)	0.007
The onset of COVID-19, days^#	3.5(2.0,7.0)	6.0(2.0,8.0)	0.348
Enrollment COVID-19 severity			0.988
Mild	25 (28.4%)	7 (25.9%)
Moderate	6 (6.8%)	2 (7.4%)
Severe	11 (12.5%)	3 (11.1%)
Critical	46 (52.3%)	15 (55.5%)
Enrollment KDIGO stage			<0.001
Stage 2	58 (65.1%)	6 (22.2 %)
Stage 3	30 (34.9%)	21 (77.8%)
The duration of disease, days^#		2.0 (1.0,3.0)

*Bold values indicate significant difference.

^#nonparametric distributions variables were expressed as median [Q1, Q3].

Abbreviations: AKI: acute kidney injury; Scr: serum creatinine; PaO₂: partial pressure of oxygen; SpO₂: arterial blood oxygen saturation; P/F: the ratio of pressure of oxygen and the fraction of inspired oxygen; WBC: white blood count; CRP: C reactive protein; IL-6: interleukin-6; SOFA: Sequential Organ Failure Assessment; KDIGO: The Kidney Disease: Improving Global Outcomes.

Figure 2. Chemokine levels in the non-PS-AKI and PS-AKI groups. IL-8: interleukin-8; CCL5: C-C chemokine ligand 5; CXCL9: chemokine (C-X-C Motif) ligand 9; IP-10: interferon-inducible protein 10; PS-AKI: persistent severe AKI. *p < 0.05.

Figure 3. The impact of septic shock on chemokine levels in the non-PS-AKI and PS-AKI groups. IL-8: interleukin-8; CCL5: C-C chemokine ligand 5; CXCL9: chemokine (C-X-C Motif) ligand 9; IP-10: interferon-inducible protein 10; PS-AKI: persistent severe AKI. *p < 0.05. **p < 0.01.

Figure 4. Correlation between plasma IL-8 levels and other clinical parameters. sCr: serum creatinine; IL-6: interleukin-6; IL-8: interleukin-8.

Figure 5. Receiver operating characteristic curve of clinical indicators for the diagnostic prediction of PS-AKI. IL-8: interleukin-8; sCr: serum creatinine; PS-AKI: persistent severe AKI.

Table 2. The diagnostic efficacy of various indicators for PS-AKI.

Indicators	AUC	95%CI	P value	Optimal threshold	Sensitivity(%)	Specificity(%)	Youden Index
SCr(μmoI/L)	0.669	0.546–0.791	0.008	140	70.4	61.4	0.317
IL-8(pg/mL)	0.769	0.675–0.863	<0.001	32.2	92.6	51.1	0.517
IL-6(pg/mL)	0.714	0.609–0.819	0.001	83.365	85.2	56.8	0.420

Abbreviations: PS-AKI: ersistence severe acute kidney injury; sCr: serum creatinine; IL-8: interleukin-8; IL-6: interleukin-6.

Table 3. The values of IL-8 for PS-AKI by multivariate logistic regression analysis.

Variables	Non-PS-AKI	PS-AKI	Crude		Adjusted
	(N = 88)	(N = 27)	OR (95%CI)	P	OR (95%CI)	P
IL-8 < 20.6 pg/mL	36(40.9%)	1(3.7%)	1.0	–	1.0	–
20.6 ≤ IL-8 ≤ 32.2 pg/mL	16(18.2%)	1(3.7%)	2.25(0.13,38.27)	0.575	2.51(0.15,43.24)	0.526
IL-8 > 32.2 pg/mL	36(40.9%)	25(92.6%)	25.0(3.21,194.5)	0.002	26.7(3.4,210.7)	0.002

*Bold values indicate significant difference.

^#Adjusted for age, sex and septic shock.

Abbreviations: PS-AKI: ersistence severe acute kidney injury; IL-8: interleukin-8.

Data availability statement

The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.