Table 1. Baseline characteristics of the study cohort by AKI and no AKI.

Variable	Total (N = 877)	No AKI (N = 540)	AKI (N = 337)	p value
Age [years], mean (SD)	55.9 (15.7)	54.5 (15.6)	58.2 (15.6)	<0.001*
Male [N (%)]	548 (62.5)	321 (59.4)	227 (67.3)	0.02*
Body Mass Index [kg/m2], mean (SD)	28.1 (6.3)	28.3 (6.2)	27.7 (6.5)	0.06
Comorbidities [N (%)]
Diabetes	311 (35.4)	153 (28.3)	158 (46.8)	<0.001*
Hypertension	332 (37.8)	161 (29.8)	171 (50.7)	<0.001*
CKD	97 (11)	16 (2.9)	81 (24)	<0.001*
Stroke	37 (4.2)	15 (2.7)	22 (6.5)	0.01*
COPD	27 (3.0)	13 (2.4)	14 (4.1)	0.14
Admission biochemical data, mean (SD)
Serum Ferritin [ng/m]	1144 (2068)	940 (2350)	1484 (2962)	<0.001*
Serum Leukocytes [109/L]	4.2 (5.2)	4.1 (4.7)	4.4 (6.0)	0.98
Serum Lymphocytes [μL]	1130 (1297)	1190 (784)	1037 (1824)	<0.001*
Serum Hemoglobin [g/dL]	13.7 (2.3)	14.1 (2.1)	13.2 (2.6)	<0.001*
Serum Platelets [109/L]	245 (156)	249 (100)	240 (216)	0.56
Serum Sodium [mEq/L]	136 (7.4)	136.3 (8.1)	135.5 (6.2)	0.26
Serum Potassium [mEq/L]	4.1 (0.8)	4 (0.7)	4.4 (0.9)	<0.001*
Arterial pH	7.41 (0.1)	7.43 (0.1)	7.40 (0.1)	0.76
Serum bicarbonate [mEq/L]	21.6 (4.6)	22.2 (4.5)	20.8 (4.6)	0.001*
Serum Creatinine [mg/dL]	1.7 (3.3)	0.8 (0.4)	2.9 (5.0)	<0.001*
COVID severity [N (%)]				<0.001*
Mild	511 (58.2)	370 (68.5)	141 (41.8)
Severe	366 (41.8)	170 (31.5)	196 (58.2)
Need in mechanical lung ventilation [N (%)]	219 (24.9)	73 (13.5)	146 (43.3)	<0.001*
Length of stay, days, mean (SD)	9.9 (6.7)	9.0 (6.2)	11.4 (7.2)	<0.001*
Disposition [N (%)]				<0.001*
Discharged	597 (68.1)	429 (79.4)	168 (49.8)
Expired	280 (31.9)	111 (20.6)	169 (50.2)

AKI, acute kidney injury; CKD, chronic kidney disease; COPD, chronic obstructive pulmonary disease; KRT, kidney replacement therapy.