Risk factors and prediction of acute kidney injury after liver transplantation: Logistic regression and artificial neural network approaches

Table 1 Diagnostic criteria for kidney dysfunction in cirrhosis (Wong et al[22], 2011)

Diagnosis	Definition
AKI	Rise in serum creatinine of > 50% from baseline or rise of sCr by > 26.4 mmol/L (> 0.3 mg/dL) in < 48 h; HRS type 1 is a specific form of AKI
CKD	eGFR of < 60 mL/min for > 3 mo calculated using MDRD6 formula; HRS type 2 is a specific form of CKD
ACKD	Rise in serum creatinine of > 50% from baseline or rise of sCr by > 26.4 mmol/L (> 0.3 mg/dL) in < 48 h in a patient with cirrhosis whose eGFR is < 60 ml/min for > 3 mo calculated using MDRD6 formula

AKI: Acute kidney injury; sCr: Serum creatinine; HRS: Hepatorenal syndrome; CKD: Chronic kidney disease; eGFR: Estimated glomerular filtration rate; ACKD: Acute on chronic kidney disease; MDRD6: Modification of Diet in Renal Disease 6.

Table 2 Definition and classification of acute kidney injury for patients with liver cirrhosis according to the International Club of Ascites (Angeli et al[23], 2015)

Baseline sCr	A sCr value obtained in 3 mo prior to hospital admission, with preference to the value dated the closest to hospital admission. In patients without a previous sCr value, the value on admission should be used
AKI definition	Increase in sCr ≥ 0.3 mg/dL (≥ 26.5 µmol/L) within 48 h; or the percentage increase in sCr ≥ 50%, which occurred in the last 7 d
Stage 1 AKI	Increase in sCr ≥ 0.3 mg/dL (26.5 µmol/L) or an increase of 1.5 to 2 times the baseline value
Stage 2 AKI	Increase of sCr 2 to 3 times the baseline value
Stage 3 AKI	Increase in sCr > 3 times the baseline or sCr ≥ 4.0 mg/dL (353.6 µmol/L), with acute increase in sCr ≥ 0.3 mg/dL (26.5 µmol/L) or onset of RRT

AKI: Acute kidney injury; ICA: International Club of Ascites. sCr: Serum creatinine; RRT: Renal replacement therapy.

Table 3 Diagnostic criteria and hepatorenal syndrome subtypes (Angeli et al[23], 2015)

Diagnostic criteria for HRS

HRS subtype

1) Presence of cirrhosis or ascites; 2) sCr > 1.5 mg/dL or 133 µmoles/L; 3) No improvement in sCr (below 1.5 mg/dL) after at least 48 h of diuretic withdrawal and volume expansion with albumin; 4) Absence of shock; 5) Has not undergone recent treatment with nephrotoxic drugs; 6) Absence of parenchymal kidney disease as indicated by proteinuria less than 500 mg/d, microhematuria (less than 50 erythrocytes/high-magnification field), and/or abnormal renal ultrasound findings

HRS type 1-Rapidly progressive renal failure defined as the doubling of initial serum creatinine to a level greater than 2.5 mg/dL or 220 µmoles/L in less than 3 wk, and associated with a very poor prognosis; HRS type 2-Moderate renal failure (sCr > 1.5 mg/dL or 133 µmoles/L), following a stable or slowly progressive course, often associated with refractory ascites

HRS: Hepatorenal syndrome; sCr: Serum creatinine.

Table 4 Acute kidney injury stages according to International Club of Ascites criteria (n = 145)

Overall incidence (n = 88)	Stage 1 (n = 22)	Stage 2 (n = 36)	Stage 3/RRT (n = 30/12)
60.6%	15.1%	24.8%	20.6/8.7%

RRT: Renal replacement therapy.

Table 5 Patients’ preoperative baseline information according to the occurrence of acute kidney injury after deceased-donor liver transplantation (n = 145)

	No AKI (n = 57)	AKI (n = 88)	P value
Male gender, n (%)	29 (50.8)	49 (55.6)	0.441
Age (yr), mean (± SD)	53.2 (± 13.56)	56.2 (± 13.26)	0.352
BMI, mean (± SD)	18.2(± 4.54)	22.7 (± 4.92)	0.065
Biological MELD score, mean (± SD)	21.67 (± 2.15)	26.05 (± 3.05)	< 0.001
Previous ascites, n (%)	24 (42.1)	52 (59.0)	0.013
Previous encephalopathy, n (%)	18 (31.5)	39 (44.3)	0.025
Previous upper digestive bleeding, n (%)	21 (36.8)	45 (51.1)	0.018
Preexisting KD, n (%)	15 (26.3)	60 (68.1)	< 0.001
HCC, n (%)	20 (35.0)	37 (42.0)	0.069
Systemic arterial hypertension, n (%)	28 (49.1)	46 (52.2)	0.083
Diabetes mellitus, n (%)	23 (40.3)	43 (48.8)	0.254

AKI: Acute kidney injury; LT: Liver transplantation; SD: Standard deviation; KD; Kidney dysfunction; BMI: Body mass index; MELD: Model for End-stage Liver Disease; HCC: Hepatocellular carcinoma.

Table 6 Donor and graft characteristics according to the occurrence of acute kidney injury after deceased-donor liver transplantation (n = 145)

	No AKI (n = 57)	AKI (n = 88)	P value
Donor > 60 yr, n (%)	16 (28.0)	31 (35.2)	0.346
Donor BMI > 27-30 kg/m2, n (%)	14(24.5)	28 (31.8)	0.039
Graft macrosteatosis > 30%, n (%)	11 (19.2)	32 (36.3)	0.024
GCIT > 8 h, n (%)	0	0	-
GWIT > 40-45 min	38 (66.6)	54 (61.3)	0.349
Donor ICU stay > 4 d, n (%)	11 (19.2)	22 (25.0)	0.088
Donor controlled sepsis, n (%)	05 (8.7)	11 (12.5)	0.061
History of alcoholism of donor, n (%)	08 (14.0)	15 (17.0)	0.255
Donor sCr > 1.2 mg/dL, n (%)	16 (28.0)	31 (35.2)	0.024
Donor hypotensive episodes (< 60 mmHg) > 1 h, n (%)	10 (17.5)	18 (20.4)	0.127
Donor serum bilirubin > 2.0 mg/dL, n (%)	25 (43.8)	48 (54.5)	0.087
Donor serum ALT > 170 U/L, n (%)	11 (19.2)	22 (25.0)	0.073
Donor serum AST > 140 U/L, n (%)	05 (8.7)	13 (14.7)	0.023
Use of dopamine doses > 10 microg/kg per min, n (%)	10 (17.5)	13 (14.7)	0.176
Donor peak serum sodium > 155 mEq/L, n (%)	02 (3.5)	5 (5.6)	0.219
ECD (3 or more factors above), n (%)	07 (12.2)	31 (35.2)	< 0.001

AKI: Acute kidney injury; LT: Liver transplantation; BMI: Body mass index; GCIT: Graft cold ischemia times; GWIT: Graft warm ischemia times; ICU: Intensive care unit: sCr: Serum creatinine; ALT: Alanine transaminase; AST: Aspartate transaminase; ECD: Extended criteria donor.

Table 7 Intraoperative events in 145 deceased-donor liver transplantations according to the occurrence of postoperative acute kidney injury

	Without AKI (n = 57)	With AKI (n = 88)	P value
IOAH (bleeding/PRS), n (%)	14 (24.5)	54 (61.3)	< 0.001
MBT, n (%)	5 (8.7)	15 (17.0)	< 0.001
Vasoactive drugs, n (%)	38(66.6)	48 (54.5)	0.197
Cryoprecipitate transfusion, n (%)	10 (17.5)	18 (20.4)	0.169
Piggy-back clamping, n (%)	30 (52.6)	48 (54.5)	0.072
SL (mmol/L) at the end of LT, mean (± SD)	1.4 (± 0.3)	2.8 (± 0.7)	< 0.001
Lower serum fibrinogen (mg/dL), mean (± SD)	242 (± 34)	214 (± 24)	0.090

AKI: Acute kidney injury; IOAH: Intraoperative arterial hypotension; MBT: Massive blood transfusion; SL: Serum lactate; SD: Standard deviation.

Table 8 Logistic regression analysis of risk factors for acute kidney injury after deceased-donor liver transplantation (n = 145)

Logistic regression	Beta coeficient	OR	95%CI		P value
Biological MELD score ≥ 25	0.194	1.999	1.586	2.503	< 0.001
Pre-existing KD, n (%)	0.115	1.279	0.916	1.686	< 0.001
ECD (3 or more factors above)	0.911	1.191	0.711	1.787	0.002
IOAH (bleeding/PRS), n (%)	0.169	1.935	1.505	2.344	< 0.001
MBT, n (%)	0.125	1.830	1.428	2.241	< 0.001
SL (mmol/L) ≥ 2.0 at the end of LT	0.110	2.001	1.616	2.421	< 0.001

Hosmer and Lemeshow goodness of fit test not significant at 5% (P = 0.701); Nagelkerke R2 statistic = 0.163). LR: Logistic regression; AKI: Acute kidney injury; MELD: Model for End-stage Liver Disease; OR: Odds ratio; CI: Confidence interval; KD: Kidney dysfunction; ECD: Extended criteria donor; IOAH: Intra-operative arterial hypotension; MBT: Massive blood transfusion; SL: Serum lactate.