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Table 1 Descriptive of the included papers (n = 20)

From: Transforming liver transplant allocation with artificial intelligence and machine learning: a systematic review

Paper

Data Source type and number(location)

Sample (n)

Outcome (positive outcome rate/%*)

Number of input features used

Categories of features

Best performing model

Types of models

Main performing metrics

Recipient (n)

Donor (n)

Operative (n)

Cruz-Ramírez et al. (2011) [24]

11 Hospitals (Spain)

1001

12-month graft mortality (16.1)

42

19

20

3

MPDENN_C, MPDENN_MS

Classification (Neural Network)

MPDENN-E C = 84.46; MPDENN-MS MS = 45.55

Cruz-Ramírez et al. (2011) [25]

11 Hospitals (Spain)

1003

3-month graft survival (NA)

39

16

20

3

MPDENN-E, MPDENN-MS

Classification (Neural Network)

MPDENN-E C = 89.29, MS = 13.79, RMSE = 0.3212; MPDENN_MS C = 63.89, MS = 62.07, RMSE = 0.3863

Cruz-Ramírez et al. (2012) [26]

11 Hospital (Spain)

1001

1-year graft survival (16.1)

41

16

16

9

MPDENN-E, MPENSGA-2

Classification (Neural Network)

MPDENN-E C = 83.68,

MRSE = 0.3795; MPENSGA2-MS MS = 52.04,

AUC = 0.5694

Cruz-Ramírez et al. (2014) [27]

11 Hospital (Spain)

1003

3-month graft mortality (NA)

57

26

19

12

NN

Classification (Neural Network)

NN-CCR (Correct classification rate) = 90.79%, NN-MS(Minimum sensitivity) = 71.42%

Briceno et al. (2013) [28]

11 Hospital (Spain)

1003

3-month graft mortality (NA)

39

16

20

3

MPENSGA-2

Classification (Neural Network)

MS = 48.98,

AUC = 0.5659

Pérez-Ortiz et al. (2017) [29]

11 Hospital (UK)

822

3- and 12- month graft survival (NA)

37

16

17

4

LSVC (for 3- months), CSSVC (for 12-months)

Classification (Linear, non-Linear, Neural Network)

LSVC Acc = 90.15, CSSVC Acc = 90.15

Dorado-Moreno et al. (2017) [30]

Hospitals (7 Spain, 1 UK)

1,406

< 15-days, 15-90-days, and 90-365-days graft survival (NA)

38

16

17

5

DIM-ORNET

Classification (Neural Network)

Acc = 73.57%, geometric mean sensitivity (GMS) = 31.46%,

Average mean absolute error (AMAE) = 1.155

Guijo-Rubio et al. (2021) [31]

1 Registry (UNOS, US)

39,189

3-months (7.7), 1-year (15.3), 2-years (22.1), 5-years (76.8) graft survival

28

15

11

2

LR

Classification (Linear, Decision Trees)

LR: AUC = 0.654, Acc = 0.614, MS = 0.584

Zhang et al. (2022) [32]

1 Registry (UNOS, US)

3-month: 478,777,

1-year: 47,401, 3-years: 6,380, 5-years: 45,270, 10-years: 20,751

3-month (6.4), 1-year (12.5), 2-years (21.2), 3-years (21.28), 5-years (27.8), 10-years (45.3) recipient mortality

42

   

XGBoost

Classification (Decision Tree)

AUC = of 0.717 for 3 months,

0.681 for 1 year, 0.662 for 3 years, 0.660 for 5 years, and 0.674 for 10 years.

Andres et al. (2018) [33]

1 Registry (SRTR, US)

2,769

0.25-year, 1-year, 3-years, 5-years, 10-years recipient survival (NA)

4

4

  

Cox model

Regression (Linear)

C-statistics for 0.25 year = 95.6%, 1 year = 93%, 3 year = 87.6%, 5 year = 84.1%, and 10 year = 72%

Lau et al. (2017) [34]

1 Hospital (Australia)

180

30-days (8.8), and 3-months graft failure (6.1)

15

3

12

 

NN

Classification (Neural Network)

AUC = 0.835

Farzindar et al. (2019) [35]

2 Registry (UNOS and SRTR, US)

87,334

Precise time of failure (Time to event) (NA)

    

Deep survival model

Regression (Deep survival model)

C-index = 0.82 during development and 0.57 during testing

Ershoff et al. (2020) [36]

1 Registry (UNOS, US)

57,544

90 days recipient mortality (5.4)

202

132

70

 

DNN

Classification (Neural Network)

AUC = 0.703

Kwong et al. (2021) [37]

1 Registry (OPTN, US)

18,920

Waitlist dropout at 3-months (6.5), 6-months (11.3), 12-months (17.2)

12

12

  

Cox model

Regression (Linear)

C-statistic = 0.74.

Kantidakis et al. (2020) [38]

1 Registry (UNOS, US)

62,294

Overall graft survival (NA)

97

52

45

 

RF and NN

Regression (Linear)

RF: C-index = 0.622 NN: IBS = 0.180

Yu et al. (2022) [39]

1 Registry (Korea)

785

1-month (8.1), 3-months (11.2), 12-months (17.2) recipient survival

    

RF

Classification (Decision Tree)

AUC = 0.80 for 1 month, 0.85 for 3 months, and 0.81 for 12 months

Börner et al. (2022) [40]

1 Hospital (Germany)

529

2-months, 6-months, 9-months, 12-months in-hospital recipient survival (NA)

48

24

20

4

DNN

Classification (Neural Network)

Acc = 95.8% and AUC = 0.940

Lankarani et al. (2022) [41]

1 Center (Iran)

1,947

2-years waitlist mortality (18.4)

25

25

  

ANN, SVM

Classification (Neural Network)

MELDNa < 23, age < 53, and ALP < 257 were the best predictors of survival in candidates

Raju et al. (2023) [42]

1 Registry (UNOS, US)

62,556

90 days recipient mortality (NA)

29

29

  

FT-Transformer

Classification (Neural Network)

AUC = 0.96–0.98, Acc = 0.89

Ivanics et al. (2023) [43]

3 Registry (UNOS/US, Canadian, UK)

UNOS = 59,558, Canada = 1,214, UK = 5287,

90-days recipient mortality (NA)

23

15

4

4

Ridge-Logistic regression

Classification (Linear)

AUC = 0.74 − 0.71. External model performance across countries overall had poor performed

  1. Note: *Positive outcome rate = Number of positive outcomes (cases) divided by the total number of exposed (cases and non-cases)