Prognostic significance of early acute kidney injury in COVID-19 patients requiring mechanical ventilation: a single-center retrospective analysis

Figures & data

Table 1. Baseline characteristics of the patients.

	All	no AKI	AKI Stage 1	AKI Stage 2	AKI Stage3
Number	372	297	33	28	14
Age	61.0 (17.3)	60.0 (17.3)	67.0 (17.3)	65.0 (17.3)	68.0 (17.3)	years
Male gender	76.6	75.1	75.8	92.9	78.6	%
BMI	29.4 (8.7)	29.4 (9.2)	29.7 (10.1)	29.6 (8.5)	30.5 (10.9)	kg.m^-2
OI on admission	92.7 (54.5)	92.7 (55.4)	97.0 (51.4)	104.4 (48.9)	92.0 (66.9)	mmHg
Smoking status	16.5	17.1	15.4	15.4	9.1	%
Arterial hypertension	55.9	52.2	63.6	75.0	78.6	%
Diabetes mellitus	23.4	21.2	27.3	39.3	28.6	%
COPD	5.1	4.4	6.1	14.3	0.0	%
Chronic heart failure	5.4	3.7	9.1	14.3	14.3	%
Coronary artery disease	8.1	7.7	3.0	14.3	14.3	%
Arrhythmia	6.2	5.1	15.2	10.7	0.0	%
Stroke	2.4	1.7	6.1	7.1	0.0	%
PVD	2.4	1.0	3.0	14.3	7.1	%
Liver disease	3.2	3.0	6.1	3.6	0.0	%
Malignancy	5.4	4.7	6.1	10.7	7.1	%
Connective tissue disease	4.0	4.4	6.1	0.0	0.0	%
Peptic ulcer disease	3.5	3.4	6.1	3.6	0.0	%
CKD Stage 1-2	2.9	0.3	9.1	14.3	21.4	%
CCI	2.0 (2.0)	2.0 (2.0)	3.0 (3.0)	3.0 (2.25)	2.5 (1.0)

BMI: body mass index; COPD: chronic obstructive pulmonary disease; PVD: peripheral vascular disease; CKD: chronic kidney disease; CCI: Charlson comorbidity index.

Figure 1. Kaplan–Meier survival curves for 90-day mortality from ICU admission stratified by AKI stage on ICU admission. No data were censored before Day 90.

Figure 2. Cox regression analysis of the impact of AKI stage on ICU admission on ICU mortality and 90-day mortality adjusted for age, BMI, sex and comorbidities. HR, hazard ratio; aHR, adjusted hazard ratio; CCI, Charlson comorbidity index.

Table 2. Mortality and the need for RRT depending on AKI stage on ICU admission.

AKI stage	n	RRT	ICU mortality	90D mortality
All	372	17.5	38.4	50.0
no AKI	297	10.8	34.7	44.4
1	33	21.2	39.4	57.6
2	28	50.0	57.1	78.7
3	14	85.7	78.6	92.9
p value		<0.001	<0.001	<0.001

Values are expressed in percents; p values result from log-rank tests.

Table 3. Development of AKI stage from Day 0 to Day 2. The values indicate numbers of patients with corresponding AKI stage on Day 0 (in rows) and on Day 2 (in columns).

AKI stage		Day 2
		no AKI	1	2	3	Σ
Day 0	no AKI	279	10	4	4	297
	1	15	7	6	5	33
	2	4	9	8	7	28
	3	1	0	0	13	14
	Σ	299	26	18	29	372

Table 4. Association of mortality and the need for RRT with the change in AKI stage from Day 0 to Day 2.

change in AKI stage	n	RRT	ICU mortality	90D mortality
increase	36	47	58	75
no change	299	11	35	46
decrease	29	21	34	52
p value		<0.001	<0.001	<0.001

Values are expressed in percents; p values result from log-rank tests.

Figure 3. Kaplan–Meier survival curves for 90-day mortality from ICU admission stratified by change in creatinine within 48 h of ICU admission by more than 20%. No data were censored before Day 90.

Figure 4. Cox regression analysis of the impact of change in creatinine within 48 h of ICU admission on ICU and 90-day mortality after being adjusted for age, BMI, gender and comorbidities. Stationary creatinine was used as a reference. The decrease and increase in creatinine were defined by a change in creatinine of more than 20%. HR: hazard ratio; aHR: adjusted hazard ratio; CCI: Charlson comorbidity index.

Table 5. Association of mortality and the need for RRT with a change in creatinine within 48 h of ICU admission by more than 20%.

change in creatinine level	n	RRT	ICU mortality	90D mortality
increase	61	38	57	70
no change	211	12	35	45
decrease	92	10	29	42
p value		<0.001	<0.001	<0.001

Values are expressed in percents; p values result from corresponding log-rank tests.

Table 6. Association of mortality with the need for RRT and ECMO.

RRT	ECMO	n		ICU mortality		90D mortality
yes	Yes	65	22	72	73	85	77
	No		43		72		88
no	Yes	307	64	31	50	43	57
	No		243		26		39
p value				0.0002		0.0015

Values are expressed in percents; p values result from Fisher exact test.

Figure 5. Number of COVID-19 ICU admissions per month.

Table 7. Development of need for RRT and mortality over three waves of COVID-19 in all patients and in patients requiring RRT.

COVID-19 wave	SARS-CoV-2 variant			ICU mortality		90D mortality
		n	RRT	all	RRT	all	RRT
03-12/2020	Czech	108	18.5	38.9	75.0	53.7	90.0
01-08/2021	alpha	195	16.4	41.0	87.5	50.3	90.6
09-12/2021	delta	69	18.8	30.1	30.8	43.5	61.5
p value					0.0002		0.180

Values are expressed in percents; p values result from Fisher exact test.

Data availability statement

Analyses of all data performed during this study are included in this manuscript. The datasets used and analyzed during the study are available from the corresponding author on reasonable request.