Prevalence and outcome of acute kidney injury, as defined by the new Kidney Disease Improving Global Outcomes guideline, in very low birth weight infants

Table 1 Characteristics of the 293 studied infants, n (%) unless stated otherwise

Males	142 (48)
Birth weight (g): median (range)	1130 (450-1860)
Gestational age (mean, SD)	28.7 (2.8)
Mode of delivery
Vaginal delivery	53 (18)
Cesarean section	240 (82)
Maternal steroids	217 (74)
Intraventricular hemorrhage
Grade 1	16 (5)
Grade 2	10 (3)
Grade 3	13 (5)
Grade 4	16 (5)
Periventricular leukomalacia	12 (4)
Necrotizing enterocolitis	30 (10)
Patent ductus arteriosus
Tiny	34 (11)
Moderate	39 (13)
Large	25 (8)
Sepsis
Clinical sepsis	61 (21)
Sepsis with normotension	24 (8)
Sepsis with hypotension	26 (9)
Duration of mechanical ventilation (d): median (range)	3 (1-410)
Surgery required	22 (7)
Inotrope use	59 (20)
Ibuprofen use	63 (21)
Vancomycin use	84 (29)
Gentamycin use	203 (69)
Post natal Steroids use	38 (13)
Umbilical arterial catheter use	158 (54)
Oliguria
< 0.5 mL/kg per hour for 6 h	3 (1)
< 0.3 mL/kg per hour for 24 h	10 (3)
Hypotension	58 (20)
Normal saline intravenous bolus	50 (17)
Furosemide	12 (4)
Duration of hospital stay (d): median (range)	49 (1-480)
Acute kidney injury
Stage 1	6 (2)
Stage 2	12 (4)
Stage 3	16 (5)
Mortality	46 (17)

Table 2 Stages of acute kidney injury in 34 infants by birth weight n (%)

AKI stages	Birth weight		Total n = 293
	≥ 1000 g n = 184	< 1000 g n = 109
1	2 (1.0)	4 (3.7)	6 (2.0)
2	3 (1.6)	9 (8.2)	12 (4.1)
3	5 (2.7)	11 (10.1)	16 (5.4)
Total	10 (5.4)	24 (22.0)	34 (11.6)

AKI: Acute kidney injury.

Table 3 Patients with or without acute kidney injury, n (%) unless stated otherwise

	No AKI n = 259	Stage 1 AKI n = 6	Stage 2 AKI n = 12	Stage 3 AKI n = 16	Univariate analysis P value	Multivariate analysis4P value
Males	122 (47)	4 (67)	7 (58)	9 (56)	0.61	NS
Birth weight (g): mean (SD)	1130 (267)	976 (271)	791 (257)	850 (253)	< 0.0012	NS
Gestational age (wk): median (range)	29.0 (22-35)	28.0 (23-32)	25.0 (23-30)	25.5 (23-38)	< 0.0013	NS
Mode of delivery					0.031	NS
Vaginal delivery	40 (15)	1 (17)	3 (25)	9 (56)		NS
Cesarean section	219 (84)	5 (83)	9 (75)	7 (43)		NS
Maternal steroids	193 (74)	5 (83)	8 (67)	11 (69)	0.91	NS
Intraventricular hemorrhage					< 0.0011	NS
Grade 1	15 (6)	1 (16)	0 (0)	0 (0)		NS
Grade 2	8 (3)	1 (16)	0 (0)	1 (6)		NS
Grade 3	9 (3)	1 (16)	1 (8)	2 (13)		NS
Grade 4	9 (4)	0 (0)	1 (8)	6 (40)		NS
Necrotizing enterocolitis	16 (6)	1 (16)	6 (50)	7 (43)	< 0.0011	0.001
Patent ductus arteriosus					0.031	NS
Tiny	29 (11)	1 (16)	1 (8)	3 (18)		NS
Moderate	32 (12)	0 (0)	3 (25)	4 (25)		NS
Large	19 (7)	1 (16)	3 (25)	2 (12)		NS
Sepsis					< 0.0011	NS
Clinical sepsis	45 (17)	3 (50)	6 (50)	7 (43)		NS
Sepsis with normotension	22 (8)	1 (16)	0 (0)	1 (6)		NS
Sepsis with hypotension	14 (5)	1 (16)	6 (50)	5 (31)		NS
Duration of mechanical ventilation (d): median (range)	2 (1-160)	3.5 (1-29)	17.5 (7-71)	13 (2-262)	< 0.0013	NS
Surgery required	11 (4)	1 (16)	4 (33)	6 (37)	< 0.0011	NS
Inotrope use	37 (14)	2 (33)	8 (66)	12 (75)	< 0.0011	NS
Ibuprofen use	51 (19)	1 (16)	7 (58)	4 (25)	0.011	NS
Vancomycin use	59 (22)	3 (50)	10 (83)	12 (75)	< 0.0011	NS
Gentamycin use	173 (66)	5 (83)	11 (91)	14 (87)	0.081	NS
Steroids use	24 (9)	1 (16)	6 (50)	7 (43)	< 0.0011	NS
Umbilical arterial catheter use	129 (49)	5 (83)	8 (66)	16 (100)	< 0.0011	NS
Oliguria					< 0.0011	NS
< 0.5 mL/kg per hour for 6 h	0 (0)	0 (0)	1 (8)	2 (12)		NS
< 0.3 mL/kg per hour for 24 h	0 (0)	1 (16)	3 (25)	6 (37)		NS
Hypotension	35 (13)	2 (33)	9 (75)	12 (75)	< 0.0011	NS
Normal saline intravenous bolus	28 (10)	2 (33)	9 (75)	11 (68)	< 0.0011	NS
Furosemide	4 (1)	1 (16)	3 (25)	4 (25)	< 0.0011	NS
Duration of hospital stay in survivors (d): median (range)	52 (15-280)	64.5 (53-125)	74.5 (7-116)	116 (44-362)	0.023	NS
Mortality	27 (10)	2 (33)	8 (66)	9 (56)	< 0.0011	NS
Serum creatinine (µmol/L) on discharge: median (range)	44 (23)	64 (56)	93 (47)	133 (135)	< 0.0013	NS
Mean blood pressure (mmHg) on discharge: median (range)	55 (13)	48 (24)	38 (13)	41 (19)	< 0.0013	NS

¹χ² or Fisher exact test;

²Analysis of variance (ANOVA);

³Kruskal-Wallis test;

⁴Logistic regression. NS: Not significant; AKI: Acute kidney injury.

Table 4 Outcomes, n (%) unless stated otherwise

	No AKI n = 259	Any stage AKI n = 34	P value
Length of stay in survivors: median (range)
BW ≤ 1000 g (n = 108)	82 (37-280)	112 (7-362)	0.32
BW > 1000 g (n = 184)	40 (15-149)	53 (35-137)	0.0032
Mortality of any cause
BW ≤ 1000 g (n = 108)	18 (21)	14 (58)	< 0.0011
BW > 1000 g (n = 184)	9 (5)	5 (50)	< 0.0011

¹χ² or Fisher exact test;

²Kruskal-Wallis test. Number of infants in birth weight categories is not identical in all outcomes as some data was missing. AKI: Acute kidney injury; BW: Birth weight.