Machine perfusion distribution across clinical phenotypes in kidney transplantation: A national cohort study using unsupervised clustering

Table 3 Machine perfusion subgroup descriptive baseline characteristics, n (%)

Characteristic	All (n = 544)	Cluster 1 (n = 41)	Cluster 2 (n = 59)	Cluster 3 (n = 93)	Cluster 4 (n = 36)	Cluster 5 (n = 97)	Cluster 6 (n = 218)
Recipient age	55.9 (12.1)	49.5 (12.0)	62.9 (9.5)	52.9 (12.4)	53.2 (12.2)	48.9 (12.7)	60.2 (9.5)
Recipient BMI	27.7 (5.0)	26.3 (4.7)	29.1 (4.7)	28.1 (4.5)	28.2 (6.3)	26.5 (4.9)	28.0 (5.0)
Recipient sex
Female	183 (33.6)	12 (29.3)	10 (16.9)	33 (35.5)	17 (47.2)	42 (43.3)	69 (31.7)
Male	360 (66.2)	29 (70.7)	49 (83.1)	60 (64.5)	19 (52.8)	55 (56.7)	148 (67.9)
Recipient ABO blood group
A	214 (39.3)	17 (41.5)	29 (49.2)	38 (40.9)	15 (41.7)	37 (38.1)	78 (35.8)
AB	21 (3.9)	3 (7.3)	1 (1.7)	4 (4.3)	1 (2.8)	5 (5.2)	7 (3.2)
B	69 (12.7)	4 (9.8)	7 (11.9)	4 (4.3)	6 (16.7)	11 (11.3)	37 (17.0)
O	240 (44.1)	17 (41.5)	22 (37.3)	47 (50.5)	14 (38.9)	44 (45.4)	96 (44.0)
Recipient ethnicity
Asian	68 (12.5)	5 (12.2)	7 (11.9)	6 (6.5)	10 (27.8)	14 (14.4)	26 (11.9)
Black	34 (6.2)	5 (12.2)	6 (10.2)	1 (1.1)	5 (13.9)	5 (5.2)	12 (5.5)
White	420 (77.2)	28 (68.3)	44 (74.6)	85 (91.4)	16 (44.4)	74 (76.3)	173 (79.4)
Recipient diabetes	74 (13.6)	4 (9.8)	12 (20.3)	6 (6.5)	6 (16.7)	4 (4.1)	42 (19.3)
Recipient positive CMV serostatus	260 (47.8)	17 (41.5)	28 (47.5)	33 (35.5)	24 (66.7)	52 (53.6)	106 (48.6)
Dialysis status at registration
Hemodialysis	251 (46.1)	20 (48.8)	36 (61.0)	37 (39.8)	27 (75.0)	31 (32.0)	100 (45.9)
Not	211 (38.8)	12 (29.3)	20 (33.9)	43 (46.2)	7 (19.4)	45 (46.4)	84 (38.5)
Peritoneal	81 (14.9)	9 (22.0)	3 (5.1)	12 (12.9)	2 (5.6)	21 (21.6)	34 (15.6)
Dialysis at transplant	454 (83.5)	36 (87.8)	53 (89.8)	75 (80.6)	34 (94.4)	81 (83.5)	175 (80.3)
Type of dialysis at transplant
Hemodialysis	345 (63.4)	25 (61.0)	43 (72.9)	56 (60.2)	31 (86.1)	60 (61.9)	130 (59.6)
Not	1 (0.2)	1 (2.4)	0 (0.0)	0 (0.0)	0 (0.0)	0 (0.0)	0 (0.0)
Peritoneal	109 (20.0)	11 (26.8)	10 (16.9)	19 (20.4)	3 (8.3)	21 (21.6)	45 (20.6)
Donor organ
Left kidney	293 (53.9)	20 (48.8)	30 (50.8)	50 (53.8)	15 (41.7)	44 (45.4)	134 (61.5)
Right kidney	251 (46.1)	21 (51.2)	29 (49.2)	43 (46.2)	21 (58.3)	53 (54.6)	84 (38.5)
Highly sensitised status flag	26 (4.8)	2 (4.9)	1 (1.7)	4 (4.3)	4 (11.1)	10 (10.3)	5 (2.3)
Waiting list time	2.0 (1.5)	2.6 (1.7)	2.6 (1.8)	1.6 (1.2)	2.4 (1.6)	2.0 (1.6)	1.9 (1.3)
Recipient deprivation group
Quartile 1 most deprived	105 (19.3)	11 (26.8)	11 (18.6)	16 (17.2)	6 (16.7)	18 (18.6)	43 (19.7)
Quartile 2 second most deprived	82 (15.1)	4 (9.8)	15 (25.4)	10 (10.8)	6 (16.7)	9 (9.3)	38 (17.4)
Quartile 3 second least deprived	99 (18.2)	8 (19.5)	7 (11.9)	14 (15.1)	11 (30.6)	19 (19.6)	40 (18.3)
Quartile 4 least deprived	88 (16.2)	10 (24.4)	6 (10.2)	14 (15.1)	6 (16.7)	21 (21.6)	31 (14.2)
Donor age	54.7 (13.0)	46.1 (11.9)	60.2 (8.5)	54.9 (12.4)	51.9 (13.9)	41.9 (12.2)	61.0 (8.7)
Donor BMI	27.0 (5.3)	24.9 (4.3)	28.5 (5.9)	26.9 (5.2)	26.4 (4.9)	25.3 (4.3)	27.8 (5.6)
Donor sex
Female	224 (41.2)	11 (26.8)	23 (39.0)	47 (50.5)	15 (41.7)	24 (24.7)	104 (47.7)
Male	320 (58.8)	30 (73.2)	36 (61.0)	46 (49.5)	21 (58.3)	73 (75.3)	114 (52.3)
Donor ABO blood group
A	221 (40.6)	18 (43.9)	29 (49.2)	39 (41.9)	14 (38.9)	40 (41.2)	81 (37.2)
AB	12 (2.2)	2 (4.9)	1 (1.7)	2 (2.2)	1 (2.8)	2 (2.1)	4 (1.8)
B	58 (10.7)	4 (9.8)	7 (11.9)	3 (3.2)	6 (16.7)	8 (8.2)	30 (13.8)
O	253 (46.5)	17 (41.5)	22 (37.3)	49 (52.7)	15 (41.7)	47 (48.5)	103 (47.2)
Donor ethnicity
Asian	2 (0.4)	0 (0.0)	1 (1.7)	0 (0.0)	0 (0.0)	0 (0.0)	1 (0.5)
Black	1 (0.2)	1 (2.4)	0 (0.0)	0 (0.0)	0 (0.0)	0 (0.0)	0 (0.0)
White	529 (97.2)	36 (87.8)	57 (96.6)	93 (100.0)	36 (100.0)	95 (97.9)	212 (97.2)
Donor positive CMV status	250 (46.0)	16 (39.0)	25 (42.4)	37 (39.8)	19 (52.8)	44 (45.4)	109 (50.0)
Donor positive EBV status	483 (88.8)	33 (80.5)	54 (91.5)	82 (88.2)	32 (88.9)	86 (88.7)	196 (89.9)
Donor positive toxoplasmosis status	98 (18.0)	8 (19.5)	9 (15.3)	18 (19.4)	4 (11.1)	13 (13.4)	46 (21.1)
Donor cardiac disease	64 (11.8)	5 (12.2)	18 (30.5)	7 (7.5)	4 (11.1)	4 (4.1)	26 (11.9)
Donor diabetes	28 (5.1)	0 (0.0)	10 (16.9)	2 (2.2)	2 (5.6)	3 (3.1)	11 (5.0)
Donor family history of diabetes	151 (27.8)	10 (24.4)	23 (39.0)	20 (21.5)	10 (27.8)	27 (27.8)	61 (28.0)
Donor history of drug abuse	74 (13.6)	20 (48.8)	4 (6.8)	3 (3.2)	13 (36.1)	26 (26.8)	8 (3.7)
Donor hypertension	148 (27.2)	2 (4.9)	36 (61.0)	15 (16.1)	8 (22.2)	5 (5.2)	82 (37.6)
Donor smoker	306 (56.2)	29 (70.7)	39 (66.1)	50 (53.8)	26 (72.2)	68 (70.1)	94 (43.1)
Donor history of UTI	37 (6.8)	3 (7.3)	7 (11.9)	4 (4.3)	4 (11.1)	3 (3.1)	16 (7.3)
Donor allergy	162 (29.8)	16 (39.0)	29 (49.2)	26 (28.0)	18 (50.0)	15 (15.5)	58 (26.6)
Donor creatinine at retrieval	0.3 (0.5)	0.3 (0.5)	0.1 (0.4)	0.3 (0.4)	0.2 (0.4)	0.4 (0.5)	0.3 (0.5)
Donor type
DBD	33 (6.1)	3 (7.3)	3 (5.1)	6 (6.5)	5 (13.9)	5 (5.2)	11 (5.0)
DCD	511 (93.9)	38 (92.7)	56 (94.9)	87 (93.5)	31 (86.1)	92 (94.8)	207 (95.0)
Donor cause of death
Neurological	470 (86.4)	35 (85.4)	57 (96.6)	73 (78.5)	32 (88.9)	84 (86.6)	189 (86.7)
Other	49 (9.0)	1 (2.4)	0 (0.0)	15 (16.1)	2 (5.6)	11 (11.3)	20 (9.2)
Cold ischemia time	13.4 (4.7)	13.7 (4.7)	15.2 (4.6)	12.2 (4.3)	16.2 (4.7)	12.9 (4.6)	13.1 (4.7)
Perfusate used
HTK	10 (1.8)	1 (2.4)	2 (3.4)	2 (2.2)	3 (8.3)	1 (1.0)	1 (0.5)
Marshalls	112 (20.6)	3 (7.3)	14 (23.7)	21 (22.6)	2 (5.6)	15 (15.5)	57 (26.1)
Wisconsin	418 (76.8)	37 (90.2)	42 (71.2)	69 (74.2)	31 (86.1)	81 (83.5)	158 (72.5)
Perfusion quality
Fair	63 (11.6)	1 (2.4)	8 (13.6)	13 (14.0)	3 (8.3)	16 (16.5)	22 (10.1)
Good	424 (77.9)	36 (87.8)	44 (74.6)	70 (75.3)	31 (86.1)	72 (74.2)	171 (78.4)
Poor	41 (7.5)	4 (9.8)	7 (11.9)	7 (7.5)	2 (5.6)	5 (5.2)	16 (7.3)
Machine perfusion type
HMP	359 (66.0)	13 (31.7)	29 (49.2)	73 (78.5)	12 (33.3)	71 (73.2)	161 (73.9)
NMP	185 (34.0)	28 (68.3)	30 (50.8)	20 (21.5)	24 (66.7)	26 (26.8)	57 (26.1)
Donor homozygous at A locus	104 (19.1)	8 (19.5)	14 (23.7)	21 (22.6)	4 (11.1)	17 (17.5)	40 (18.3)
Donor homozygous at B locus	54 (9.9)	4 (9.8)	5 (8.5)	12 (12.9)	0 (0.0)	15 (15.5)	18 (8.3)
Donor homozygous at DR locus	88 (16.2)	5 (12.2)	7 (11.9)	34 (36.6)	1 (2.8)	17 (17.5)	24 (11.0)
Recipient homozygous at A locus	103 (18.9)	8 (19.5)	8 (13.6)	6 (6.5)	8 (22.2)	23 (23.7)	50 (22.9)
Recipient homozygous at B locus	67 (12.3)	2 (4.9)	6 (10.2)	5 (5.4)	9 (25.0)	14 (14.4)	31 (14.2)
Recipient homozygous at DR locus	94 (17.3)	1 (2.4)	3 (5.1)	6 (6.5)	13 (36.1)	23 (23.7)	48 (22.0)
Number of mismatches at A locus
One	306 (56.2)	25 (61.0)	31 (52.5)	61 (65.6)	20 (55.6)	52 (53.6)	117 (53.7)
Two	156 (28.7)	7 (17.1)	19 (32.2)	8 (8.6)	13 (36.1)	35 (36.1)	74 (33.9)
Zero	82 (15.1)	9 (22.0)	9 (15.3)	24 (25.8)	3 (8.3)	10 (10.3)	27 (12.4)
Number of mismatches at B locus
One	388 (71.3)	28 (68.3)	39 (66.1)	69 (74.2)	12 (33.3)	81 (83.5)	159 (72.9)
Two	97 (17.8)	3 (7.3)	13 (22.0)	0 (0.0)	24 (66.7)	13 (13.4)	44 (20.2)
Zero	59 (10.8)	10 (24.4)	7 (11.9)	24 (25.8)	0 (0.0)	3 (3.1)	15 (6.9)
Number of mismatches at DR locus
One	309 (56.8)	31 (75.6)	42 (71.2)	1 (1.1)	22 (61.1)	60 (61.9)	153 (70.2)
Two	37 (6.8)	0 (0.0)	3 (5.1)	0 (0.0)	14 (38.9)	4 (4.1)	16 (7.3)
Zero	198 (36.4)	10 (24.4)	14 (23.7)	92 (98.9)	0 (0.0)	33 (34.0)	49 (22.5)
HLA mismatch group
(0 DR and 2B) OR (1 DR and 1/0 B)	301 (55.3)	32 (78.0)	43 (72.9)	1 (1.1)	10 (27.8)	62 (63.9)	153 (70.2)
(1 DR and 2 B) OR (2 DR)	78 (14.3)	1 (2.4)	9 (15.3)	0 (0.0)	26 (72.2)	8 (8.2)	34 (15.6)
0 DR and 1/0 B	149 (27.4)	8 (19.5)	7 (11.9)	76 (81.7)	0 (0.0)	27 (27.8)	31 (14.2)
0 mismatches	16 (2.9)	0 (0.0)	0 (0.0)	16 (17.2)	0 (0.0)	0 (0.0)	0 (0.0)
Initial graft function
DGF	108 (19.9)	5 (12.2)	18 (30.5)	16 (17.2)	9 (25.0)	16 (16.5)	44 (20.2)
Immediate	370 (68.0)	31 (75.6)	29 (49.2)	66 (71.0)	25 (69.4)	73 (75.3)	146 (67.0)
PNF	12 (2.2)	2 (4.9)	3 (5.1)	0 (0.0)	0 (0.0)	0 (0.0)	7 (3.2)
Predniscolone/predniscone immunosuppression 3 months post-transplant
No	150 (27.6)	9 (22.0)	8 (13.6)	30 (32.3)	11 (30.6)	27 (27.8)	65 (29.8)
Yes	322 (59.2)	24 (58.5)	35 (59.3)	53 (57.0)	19 (52.8)	62 (63.9)	129 (59.2)
Graft status
Died functioning	89 (16.4)	2 (4.9)	9 (15.3)	11 (11.8)	5 (13.9)	7 (7.2)	55 (25.2)
Died unknown function	1 (0.2)	0 (0.0)	0 (0.0)	0 (0.0)	0 (0.0)	1 (1.0)	0 (0.0)
Failed	80 (14.7)	5 (12.2)	16 (27.1)	10 (10.8)	4 (11.1)	7 (7.2)	38 (17.4)
Functioning	374 (68.8)	34 (82.9)	34 (57.6)	72 (77.4)	27 (75.0)	82 (84.5)	125 (57.3)
Allocation matchability score	6.8 (2.4)	5.0 (2.4)	4.9 (2.4)	6.0 (2.4)	8.5 (1.7)	7.9 (1.9)	7.3 (2.1)
Serum creatinine (umol/L) 3-month post-transplant	154.8 (61.0)	133.6 (37.9)	219.8 (87.2)	155.1 (53.2)	132.5 (44.0)	114.6 (44.5)	164.8 (53.3)
Serum creatinine (umol/L) 12-month post-transplant	146.6 (57.2)	126.0 (36.3)	199.3 (89.6)	145.5 (56.3)	135.8 (45.1)	111.2 (39.0)	157.9 (49.1)
Follow-up time	5.5 (3.1)	3.3 (1.8)	2.1 (1.7)	6.8 (2.8)	2.4 (1.6)	7.5 (2.4)	5.9 (2.9)
Transplant year
2014	125 (23.0)	0 (0.0)	4 (6.8)	29 (31.2)	1 (2.8)	31 (32.0)	60 (27.5)
2015	80 (14.7)	0 (0.0)	3 (5.1)	19 (20.4)	0 (0.0)	21 (21.6)	37 (17.0)
2016	89 (16.4)	3 (7.3)	8 (13.6)	19 (20.4)	1 (2.8)	12 (12.4)	46 (21.1)
2017	45 (8.3)	0 (0.0)	1 (1.7)	7 (7.5)	2 (5.6)	15 (15.5)	20 (9.2)
2018	49 (9.0)	5 (12.2)	3 (5.1)	10 (10.8)	4 (11.1)	11 (11.3)	16 (7.3)
2019	49 (9.0)	9 (22.0)	6 (10.2)	6 (6.5)	4 (11.1)	5 (5.2)	19 (8.7)
2020	46 (8.5)	7 (17.1)	15 (25.4)	1 (1.1)	9 (25.0)	1 (1.0)	13 (6.0)
2021	44 (8.1)	13 (31.7)	14 (23.7)	1 (1.1)	8 (22.2)	1 (1.0)	7 (3.2)
2022	4 (0.7)	3 (7.3)	0 (0.0)	0 (0.0)	1 (2.8)	0 (0.0)	0 (0.0)
2023	2 (0.4)	1 (2.4)	1 (1.7)	0 (0.0)	0 (0.0)	0 (0.0)	0 (0.0)
2024	11 (2.0)	0 (0.0)	4 (6.8)	1 (1.1)	6 (16.7)	0 (0.0)	0 (0.0)
Kidney used by local centre
No	232 (42.6)	28 (68.3)	44 (74.6)	35 (37.6)	25 (69.4)	30 (30.9)	70 (32.1)
Yes	312 (57.4)	13 (31.7)	15 (25.4)	58 (62.4)	11 (30.6)	67 (69.1)	148 (67.9)

BMI: Body mass index; UTI: Urinary tract infection; DBD: Donation after brain death; CMV: Cytomegalovirus; DCD: Donation after cardiac death; HTK: Histidine-tryptophan-ketoglutarate solution; EBV: Epstein-Barr virus; HMP: Hypothermic machine perfusion; NMP: Normothermic machine perfusion; HLA: Human leukocyte antigen; DGF: Delayed graft function; PNF: Primary non-function.