Acute kidney injury in critically ill patients with traumatic brain injury: A single-center retrospective cohort study

Table 1 Demographic and baseline clinical characteristics of study population

Variable	Non-AKI group (n = 295)	AKI group (n = 36)	P value
Age (years)			< 0.0011
18-30	104 (35.25)	19 (52.78)
31-40	111 (37.63)	4 (11.11)
41-50	57 (19.32)	3 (8.33)
51-60	23 (7.8)	10 (27.78)
Sex			0.8311
Male	281 (95.25)	34 (94.44)
Female	14 (4.75)	02 (5.56)
Nationality			0.0911
Emirati	39 (13.22)	5 (13.89)
Non-Emirati
Asian	210 (71.19)	28 (77.78)
Middle eastern	32 (10.85)	1 (2.78)
African	11 (3.73)	0 (0)
European-American	3 (1.02)	2 (5.56)
Body mass index (kg/m2)	24 (22-26.65)	24.5 (22-27.03)	0.4362
Charlson comorbidity index	0.23 ± 0.78	0.72 ± 1.21	0.0233
Mechanism of injury			0.2161
Road traffic accident	194 (65.76)	21 (58.33)
Fall	83 (28.14)	15 (41.67)
Assault	16 (5.42)	0 (0)
Work related	2 (0.68)	0 (0)
Glasgow coma scale on admission to hospital	8 (6-11)	4 (3-8)	< 0.0012
Injury Severity Score on admission to hospital	17 (15-24.5)	23 (18-25)	0.0052
Acute physiology and chronic health evaluation-2 score on admission to intensive care unit	12 (8-18)	23 (15-28)	< 0.0012

¹Pearson χ² test.

²Mann-Whitney test.

³Independent samples t-test.

Values are presented as n (%), median (interquartile range), or mean ± SD. AKI: Acute kidney injury.

Table 2 Risk factors for acute kidney injury after traumatic brain injury, n (%)

Variable	Non-AKI group (n = 295)	AKI group (n = 36)	P value1
Shock in 24 hours			< 0.001
Yes	65 (22.03)	22 (61.11)
No	230 (77.97)	14 (38.89)
CT with contrast			0.068
Yes	229 (77.63)	23 (63.89)
No	66 (22.37)	13 (36.11)
Second CT with contrast			0.23
Yes	43 (14.58)	8 (22.22)
No	252 (85.42)	28 (77.78)
First neurosurgery			0.062
Yes	179 (60.68)	16 (44.44)
No	116 (39.32)	20 (55.56)
Type of first neurosurgery	Non-AKI group (n = 179)	AKI group (n = 16)	0.3
Major	113 (63.13)	8 (50)
Minor	66 (36.87)	8 (50)
Second neurosurgery			0.029
Yes	41 (13.9)	10 (27.78)
No	254 (86.1)	26 (72.22)
Type of second neurosurgery	Non-AKI group (n = 41)	AKI group (n = 10)	0.007
Major	38 (92.68)	6 (60)
Minor	3 (7.32)	4 (40)
Blood transfusion			0.016
Yes	22 (7.46)	7 (19.44)
No	273 (92.54)	29 (80.56)
ICP monitored			0.546
Yes	155 (52.54)	17 (47.22)
No	140 (47.46)	19 (52.78)
High ICP	Non-AKI group (n = 155)	AKI group (n = 17)	< 0.001
Yes	20 (12.9)	11 (64.71)
No	135 (87.1)	6 (35.29)
Rhabdomyolysis			< 0.001
Yes	29 (9.83)	12 (33.33)
No	266 (90.17)	24 (66.67)
Mannitol use			0.229
Yes	47 (15.93)	3 (8.33)
No	248 (84.07)	33 (91.67)
Diabetes insipidus			< 0.001
Yes	29 (9.83)	19 (52.78)
No	266 (90.17)	17 (47.22)

¹Pearson χ² test.

AKI: Acute kidney injury; CT: Computed tomography; ICP: Intracranial pressure.

Table 3 Multivariate logistic regression showing predictors of acute kidney injury

	Coefficient B	SE	Z value	P value	Odds ratio	95%CI
Constant	-6.89	0.95	7.25	< 0.001	0	0-0.01
Charlson Comorbidity Index	0.68	0.2	3.37	0.001	1.97	1.33-2.92
Acute physiology and chronic health evaluation-2	0.12	0.03	4.56	< 0.001	1.13	1.07-1.19
Shock	2.48	0.64	3.85	< 0.001	11.94	3.38-42.19
Blood transfusion	-1.29	0.69	1.87	0.062	0.27	0.07-1.07
Rhabdomyolysis	1.99	0.6	3.34	0.001	7.33	2.28-23.61
2nd neurosurgery	1.17	0.61	1.9	0.057	3.21	0.96-10.7
High intracranial pressure	1.48	0.63	2.36	0.018	4.39	1.28-14.99
Diabetes insipidus	0.87	0.54	1.62	0.106	2.38	0.83-6.8

Table 4 Outcome

Variable	Non-AKI group (n = 295)	AKI group (n = 36)	P value
LOS in hospital (day)	22 (12-58)	18 (7-41)	0.052
LOS in ICU (day)	8 (5-17)	18 (7-24.5)	0.0082
Mechanical ventilation			0.0171
Yes	228 (77.29)	34 (94.44)
No	67 (22.71)	2 (5.56)
Ventilator day	5 (1-12)	17.5 (7-24.5)	< 0.0012
Glasgow coma scale at discharge or death from ICU	14 (11-15)	3 (3-3)	< 0.0012
Tracheostomy			0.7941
Yes	68 (23.05)	9 (25)
No	227 (76.95)	27 (75)
Brain death			< 0.0011
Yes	18 (6.1)	20 (55.56)
No	277 (93.9)	16 (44.44)
28-day mortality			< 0.0011
Yes	22 (7.46)	22 (61.11)
No	273 (92.54)	14 (38.89)
More than 28-day mortality	Non-AKI group (n = 273)	AKI group (n = 14)	< 0.0011
Yes	3 (1.1)	7 (50)
No	270 (98.9)	7 (50)

¹Pearson χ² test.

²Mann-Whitney test.

Values are presented as n (%), median (interquartile range). AKI: Acute kidney injury; ICU: Intensive care unit; LOS: Length of stay.

Table 5 Descriptive statistics of acute kidney injury group, n (%)

Variable	Stage 1	Stage 2	Stage 3
Number of patients (n = 36, 100%)	18 (50)	9 (25)	9 (25)
Renal replacement therapy (n = 9, 25%)	0	0	9
Full renal recovery (n = 14, 39%)	6	2	6
Brain dead (n = 20, 56%)	7	6	7
Mortality (n = 29, 81%)
28-day mortality	11	8	3
More than 28-day mortality	2	0	5