Impact of obesity and income on the likelihood of kidney transplantation: A retrospective cohort study

Table 1 Baseline characteristics of 54891 kidney transplant candidates listed in 2020 and 2022, by body mass index subgroup, n (%)

	Body mass index (kg/m2)
Candidate characteristics, median (IQR)	18.5- < 30	30- < 35	≥ 35
	(n = 29086)	(n = 15364)	(n = 10441)
Age at registration (years)	56 (44, 65)	57 (47, 64)	53 (44, 62)
Birth sex
Female	10916 (38)	5501 (36)	4302 (41)
Male	18170 (62)	9863 (64)	6139 (59)
Race/ethnicity
Non-Hispanic White	14547 (50)	7182 (47)	4746 (45)
Non-Hispanic Black	9667 (33)	5624 (37)	4225 (40)
Hispanic/Latino	4872 (17)	2558 (17)	1470 (14)
Blood type
A	9605 (33)	5114 (33)	3511 (34)
B	4014 (14)	2151 (14)	1461 (14)
AB	1082 (4)	568 (4)	403 (4)
O	14385 (49)	7531 (49)	5066 (49)
CPRA at listing
0	24711 (85)	13089 (85)	8993 (86)
1-80	3091 (11)	1739 (11)	1112 (11)
81-94	534 (2)	216 (1)	148 (1)
95-100	750 (3)	320 (2)	188 (2)
Kidney diagnosis at listing
Diabetes	8283 (28)	6699 (44)	4599 (44)
Glomerular disease	5470 (19)	2201 (14)	1582 (15)
Hypertensive nephrosclerosis	5722 (20)	2962 (19)	2081 (20)
Other	9611 (33)	3502 (23)	2179 (21)
Peripheral vascular disease
No	25142 (86)	12843 (84)	8759 (84)
Yes	3717 (13)	2420 (16)	1611 (15)
Unknown	227 (1)	101 (1)	71 (1)
History of malignancy
No	26899 (92)	14357 (93)	9939 (95)
Yes	2187 (8)	1007 (7)	502 (5)
Prior kidney transplant
No	26999 (93)	14709 (96)	10118 (97)
Yes	2087 (7)	655 (4)	323 (3)
Distance from listing center to residence (miles)	29 (11, 86)	33 (12, 91)	33 (11, 87)
Education
High school or less	11081 (38)	6069 (40)	3963 (38)
College/technical school	7905 (27)	4381 (29)	3095 (30)
College or more	9470 (33)	4587 (30)	3146 (30)
Unknown	630 (2)	327 (2)	237 (2)
Estimated individual annual income	66000 (40000, 86000)	63000 (39000, 82000)	61000 (38000, 78000)
Estimated individual annual income
Low (≤ $45000)	9828 (34)	5610 (37)	4195 (40)
Medium (> $45000-$77000)	9270 (32)	5169 (34)	3595 (34)
High (> $77000)	9988 (34)	4585 (30)	2651 (25)
Social vulnerability index	54 (27, 78)	57 (30, 80)	56 (30, 79)
Year of listing
2020	13745 (47)	7246 (47)	4686 (45)
2022	15341 (53)	8118 (53)	5755 (55)

IQR: Interquartile range.

Table 2 Multivariable Fine-Gray proportional sub-distribution hazards model for the association of income and body mass index for time from listing to receiving a deceased or living donor kidney transplant

	Non-Hispanic White candidates		Non-Hispanic Black candidates		Hispanic/Latino candidates
Characteristic	sHR (95%CI)	P value	sHR (95%CI)	P value	sHR (95%CI)	P value
Sub-distribution hazard ratios for time from listing to receiving a deceased donor kidney transplant1
BMI
< 30	1 (Reference)		1 (Reference)		1 (Reference)
30 < 35	0.93 (0.90, 0.97)	< 0.001	0.93 (0.89, 0.96)	< 0.001	0.97 (0.91, 1.02)	0.25
≥ 35	0.82 (0.78, 0.86)	< 0.001	0.97 (0.93, 1.02)	0.21	0.94 (0.87, 1.02)	0.12
Estimated individual annual income
High income	1 (Reference)		1 (Reference)		1 (Reference)
Middle income	1.13 (1.07, 1.20)	< 0.001	1.03 (0.97, 1.10)	0.31	1.07 (0.97, 1.17)	0.19
Low income	1.34 (1.23, 1.45)	< 0.001	1.05 (0.97, 1.14)	0.25	1.20 (1.06, 1.36)	< 0.001
Sub-distribution hazard ratios for time from listing to receiving a living donor kidney transplant1
BMI
< 30	1 (Reference)		1 (Reference)		1 (Reference)
30- < 35	0.94 (0.90, 0.99)	0.01	0.95 (0.86, 1.05)	0.33	0.90 (0.81, 0.98)	0.02
≥ 35	0.83 (0.79, 0.88)	< 0.001	0.80 (0.69, 0.92)	< 0.001	0.79 (0.71, 0.89)	< 0.001
Estimated individual annual income
High income	1 (Reference)		1 (Reference)		1 (Reference)
Middle income	0.74 (0.70, 0.78)	< 0.001	0.61 (0.54, 0.69)	< 0.001	0.99 (0.89, 1.11)	0.87
Low income	0.51 (0.47, 0.56)	< 0.001	0.42 (0.37, 0.48)	< 0.001	0.80 (0.68, 0.95)	0.01

¹Models adjusted for candidate age, birth sex, blood type, calculated panel reactive antibody at listing, time on dialysis, diagnosis, history of peripheral vascular disease, prior transplant, distance from transplant center, education, social vulnerability index, and year of listing. BMI: Body mass index; sHR: Sub-distribution hazard ratio; CI: Confidence interval.

Table 3 Multivariable Fine-Gray proportional sub-distribution hazards model for the association between income and time from listing to receiving a deceased or living donor kidney transplant

	Non-Hispanic White candidates		Non-Hispanic Black candidates		Hispanic/Latino candidates
Estimated individual annual income	sHR (95%CI)	P value	sHR (95%CI)	P value	sHR (95%CI)	P value
Sub-distribution hazard ratios for time from listing to receiving a deceased donor kidney transplant1
High income	1 (Reference)		1 (Reference)		1 (Reference)
Medium	1.12 (1.06, 1.19)	< 0.001	1.03 (0.97, 1.10)	0.33	1.06 (0.97, 1.17)	0.20
Low	1.32 (1.21, 1.43)	< 0.001	1.05 (0.96, 1.14)	0.27	1.20 (1.06, 1.36)	0.01
Sub-distribution hazard ratios for time from listing to receiving a living donor kidney transplant1
High income	1 (Reference)		1 (Reference)		1 (Reference)
Medium	0.73 (0.69, 0.78)	< 0.001	0.60 (0.53, 0.68)	< 0.001	0.98 (0.88, 1.10)	0.74
Low	0.51 (0.47, 0.55)	< 0.001	0.41 (0.36, 0.47)	< 0.001	0.80 (0.67, 0.94)	0.01

¹Models adjusted for candidate age, birth sex, blood type, calculated panel reactive antibody at listing, time on dialysis, diagnosis, history of peripheral vascular disease, prior transplant, distance from transplant center, education, social vulnerability index, and year of listing. Model excludes body mass index. sHR: Sub-distribution hazard ratio; CI: Confidence interval.

Table 4 Multivariable Fine-Gray proportional sub-distribution hazards model assessing the interaction between income and body mass index for time from listing to receiving a deceased or living donor kidney transplant

	Non-Hispanic White candidates		Non-Hispanic Black candidates		Hispanic/Latino candidates
Characteristic	sHR (95%CI)	P value	sHR (95%CI)	P value	sHR (95%CI)	P value
Sub-distribution hazard ratios for time from listing to receiving a deceased donor kidney transplant1
BMI: < 30 & high income	1 (Reference)		1 (Reference)		1 (Reference)
BMI: < 30 & middle income	1.13 (1.06, 1.20)	< 0.001	0.98 (0.91, 1.06)	0.66	0.93 (0.83, 1.03)	0.16
BMI: < 30 & low income	1.34 (1.23, 1.46)	< 0.001	1.03 (0.94, 1.13)	0.49	1.16 (1.02, 1.32)	0.02
BMI: 30- < 35 & high income	0.97 (0.91, 1.03)	0.31	0.92 (0.85, 0.99)	0.04	0.83 (0.74, 0.93)	< 0.001
BMI: 30- < 35 & middle income	0.98 (0.90, 1.06)	0.58	1.05 (0.95, 1.17)	0.36	1.43 (1.23, 1.66)	< 0.001
BMI: 30- < 35 & low income	0.91 (0.83, 1.00)	0.05	0.98 (0.89, 1.08)	0.68	1.11 (0.95, 1.30)	0.18
BMI: ≥ 35 & high income	0.75 (0.69, 0.82)	< 0.001	0.86 (0.78, 0.95)	< 0.001	0.84 (0.72, 0.98)	0.03
BMI: ≥ 35 & middle income	1.09 (0.97, 1.21)	0.14	1.21 (1.06, 1.37)	< 0.001	1.31 (1.07, 1.59)	0.01
BMI: ≥ 35 & low income	1.16 (1.04, 1.30)	0.01	1.13 (1.01, 1.26)	0.03	1.07 (0.88, 1.30)	0.50
Sub-distribution hazard ratios for time from listing to receiving a living donor kidney transplant1
BMI: < 30 & high income	1 (Reference)		1 (Reference)		1 (Reference)
BMI: < 30 & middle income	0.73 (0.68, 0.78)	< 0.001	0.66 (0.57, 0.77)	< 0.001	1.11 (0.97, 1.26)	0.14
BMI: < 30 & low income	0.53 (0.49, 0.58)	< 0.001	0.41 (0.34, 0.48)	< 0.001	0.81 (0.66, 0.97)	0.03
BMI: 30- < 35 & high income	0.94 (0.88, 1.00)	0.06	0.98 (0.82, 1.16)	0.78	1.01 (0.88, 1.17)	0.84
BMI: 30- < 35 & middle income	1.04 (0.94, 1.15)	0.49	0.84 (0.65, 1.09)	0.20	0.79 (0.64, 0.96)	0.02
BMI: 30- < 35 & low income	0.96 (0.84, 1.09)	0.52	1.08 (0.83, 1.42)	0.56	0.84 (0.68, 1.05)	0.14
BMI: ≥ 35 & high income	0.86 (0.80, 0.93)	< 0.001	0.85 (0.67, 1.07)	0.17	0.81 (0.67, 0.98)	0.03
BMI: ≥ 35 & middle income	0.99 (0.88, 1.11)	0.82	0.80 (0.58, 1.11)	0.18	0.73 (0.56, 0.97)	0.03
BMI: ≥ 35 & low income	0.87 (0.75, 1.01)	0.07	1.02 (0.74, 1.41)	0.90	1.29 (0.97, 1.72)	0.08

¹Models adjusted for candidate age, birth sex, blood type, calculated panel reactive antibody at listing, time on dialysis, diagnosis, history of peripheral vascular disease, prior transplant, distance from transplant center, education, social vulnerability index, and year of listing. BMI: Body mass index; sHR: Sub-distribution hazard ratio; CI: Confidence interval.