Cardiovascular risk factors contribute to disparities in graft outcomes in African American renal transplant recipients: A retrospective analysis

Figures & data

Table I. Patient demographics (mean, median, or percentage).

Recipient characteristics	African-American (n = 576)	Non-African-American (n = 427)	p-value
Mean age (years)	48 ± 13	50 ± 14	0.011
Age > 65	9%	15%	0.007
Male (%)	56%	61%	0.106
Length of follow-up (years)	3.7 ± 2.4	4.0 ± 2.4	0.05
Pre-existing disease states (%)
Diabetes	35%	23%	< 0.001
Hypertension	97%	94%	0.032
Heart disease	19%	24%	0.087
Smoker	25%	35%	0.002
Dyslipidemia	36%	44%	0.007
Obesity	30%	25%	0.089
Pre-transplant mean BMI	26	25	0.025
Family history (%)
Diabetes	43%	26%	< 0.001
Hypertension	53%	33%	< 0.001
Dyslipidemia	2%	6%	0.002
Mean years of dialysis prior to transplant	3.8	1.9	< 0.001
History of previous renal transplant (%)	10%	14%	0.058
Current PRA			0.578
PRA > 20%	12%	10%
PRA > 80%	3.6%	3.5%
Median HLA mismatches	4.5 ± 1.3	3.5 ± 1.8	< 0.001
CMV status (%)
D+/R−	25%	23%	0.453
CIT (hrs)			0.918
Cadaveric donor	17.8 ± 8.6	17.8 ± 8.9
Mean WIT (min)	35.8 ± 14.6	34.3 ± 14.0	0.031
Donor characteristics
Donor status (%)
Living donor	7%	31%	< 0.001
Standard cadaveric donor	86%	65%	< 0.001
ECD donor	7%	5%	< 0.001
Mean donor age (years)	34 ± 15	36 ± 14	0.102
Male donor (%)	60%	55%	0.213
African American donor (%)	29%	9%	< 0.001
Mean donor BMI	26	26	0.23

BMI, body mass index; PRA, panel-reactive antibodies; HLA, human leukocyte antigen; CMV, cytomegalovirus; WIT, warm ischemic time; ECD, extended criteria donor.

Table II. Immunosuppressive regimens (percentage or mean).

Recipient characteristics	African-American (n = 576)	Non-African-American (n = 427)	p-value
Induction agent (%)			0.397
None	18%	15%
IL-2RA	55%	56%
ALA	29%	27%
Calcineurin inhibitor use (%)
Tacrolimus (FK)	50%	54%	0.535
Cyclosporine (CyA)	49%	45%
FK levels (ng/ml)
3 months	10.8	9.2	0.224
6 months	10.2	7.8	0.032
1 year	7.9	7.4	0.326
3 years	6.6	6.3	0.657
5 years	5.2	5.5	0.554
7 years	4.1	5.5	0.026
CyA levels (ng/ml)
3 months	247	256	0.482
6 months	211	220	0.485
1 year	164	159	0.667
3 years	100	96	0.623
5 years	97	70	0.048
7 years	79	80	0.919
Corticosteroid dose (mg)
1 month	20	20	0.693
3 months	10.7	11.3	0.031
6 months	9	9	0.922
1 year	8.2	8	0.308
3 years	7.1	6.7	0.364
5 years	6.4	6.5	0.67
7 years	5.8	5.9	0.785
Convert to sirolimus	21%	23%	0.397

IL-2RA, interleukin-2 receptor alpha; ALA, antilymphocyte antibodies.

Table III. Post-transplant cardiovascular risk factor control and outcomes assessment (mean or percentage).

Post-transplant cardiovascular risk factor control	African-American	Non-African-American	p-value
Hypertension
SBP post-transplant (mmHg)	138	136	0.110
Number of agents used	3.1	3.2	0.324
Post-transplant use of agents (%)
ACE/ARB	59%	62%	0.298
Beta-blocker	72%	72%	0.943
CCB	68%	68%	0.945
Loop diuretic	41%	38%	0.240
Thiazide diuretic	13%	10%	0.475
Vasodilators	43%	44%	0.898
Overall post-transplant optimal BP control (< 130 mmHg) (%)	32%	37%	0.14
Dyslipidemia
LDL post-transplant (mg/dL)	103 (n = 193)	100 (n = 178)	0.385
Overall post-transplant statin use (%)	68%	70%	0.449
LDL at goal post-transplant (< 100 mg/dl) (%)	43%	55%	0.022
Diabetes mellitus
Blood glucose post-transplant	147	147	0.862
0–6 months mean blood glucose	150	149	0.761
> 6 months mean blood glucose	150	145	0.6
Overall insulin use post-transplant	36%	31%	0.091
Overall post-transplant glucose control (∼170 mg/dl) (%)	75%	73%	0.654
0–6 months glucose control	72%	72%	1
> 6 months glucose control	75%	72%	0.488
Post-transplant graft function assessment and occurrence of risk factors
Post-transplant GFR (MDRD)
1 year	57 (n = 478)	53 (n = 340)	0.001
3 years	51 (n = 303)	50 (n = 223)	0.604
5 years	49 (n = 176)	46 (n = 139)	0.174
7 years	49 (n = 82)	46 (n = 73)	0.574
Delayed graft function (%)	17%	9%	< 0.001
Acute rejection (%)
First-year	22%	14%	0.001
Overall	30%	18%	< 0.001
NODAT (%)	13%	13%	0.932
Total incidence DM (%)	48%	37%	< 0.001

SBP, systolic blood pressure; ACE, angiotensin-converting enzyme; ARB, angiotensin II receptor blocker; CCB, calcium channel blocker; BP, blood pressure; LDL, low-density lipoprotein; GFR, glomerular filtration rate; MDRD, Modification of Diet in Renal Disease; NODAT, new-onset diabetes mellitus after transplant; DM, diabetes mellitus.

Figure 1. Kaplan–Meyer analysis of primary outcomes between African American (AA) and non-AA renal transplant recipients (RTRs). (a) Event free survival over the entire follow-up period; (b) differences in graft survival between AA and non-AA RTRs for the duration of the study period; (c) renal transplant recipient death was analyzed using Kaplan–Meyer Survival analysis.

Table IV. Cox Proportional Hazard analysis of potential risk factors of primary outcomes.

Variable	Hazard ratio (95% CI)	Hazard ratio (95% CI)	Hazard ratio (95% CI)
Post-transplant cardiovascular events (135 events)
Age (years)	1.02 (1.00–1.03)	1.01 (1.00–1.03)	1.02 (1.00–1.03)
Recipient race	1.44 (1.01–2.04)	1.12 (0.79–1.58)	1.14 (0.81–1.61)
Male gender	1.19 (0.84–1.69)	1.17 (0.84–1.63)	1.19 (0.85–1.66)
Delayed graft function		2.11 (1.43–3.13)	2.14 (1.44–3.17)
Occurrence of rejection		1.56 (1.09–2.22)	1.56 (1.10–2.23)
Diabetes mellitus (DM)		1.49 (1.01–2.19)	1.54 (1.05–2.28)
New onset DM		1.73 (1.11–2.70)	1.83 (1.17–2.86)
Post-transplant			0.72 (0.50–1.03)
Beta-blocker use
Post-transplant statin use			0.86 (0.60–1.25)
Renal allograft failure (151 events)
Age (years)	0.99 (0.98–1.00)	0.99 (0.98–1.01)	1.00 (0.99–1.02)
Recipient race	1.48 (1.06–2.08)	1.12 (0.79–1.58)	1.16 (0.82–1.67)
Male gender	0.79 (0.58–1.09)	0.73 (0.53–1.01)	0.81 (0.58–1.13)
Delayed graft function		3.09 (2.18–4.40)	2.95 (2.05–4.23)
Occurrence of rejection		2.87 (2.04–4.03)	3.02 (2.13–4.28)
Composite CV event		1.47 (1.01–2.13)	1.73 (1.19–2.53)
Diabetes mellitus (DM)		1.22 (0.82–1.83)	1.32 (0.88–1.96)
New onset DM		0.61 (0.35–1.04)	0.92 (0.53–1.61)
Dyslipidemia		0.92 (0.63–1.33)	1.31 (0.88–1.95)
Post-transplant ACEI/ARB use			0.35 (0.25–0.50)
Post-transplant			0.49 (0.35–0.68)
Beta-blocker use
Post-transplant statin use			0.38 (0.26–0.54)
Renal transplant recipient mortality (92 events)
Age (years)	1.04 (1.03–1.06)	1.04 (1.02–1.06)	1.05 (1.03–1.07)
African American race	1.20 (0.80–1.82)	0.67 (0.43–1.02)	0.70 (0.45–1.11)
Male gender	0.79 (0.52–1.19)	0.84 (0.56–1.27)	0.96 (0.63–1.46)
Years on dialysis		1.19 (1.11–1.28)	1.23 (1.15–1.32)
Delayed graft function		2.65 (1.69–4.16)	2.85 (1.79–4.53)
Composite CV event		1.91 (1.23–2.96)	2.33 (1.48–3.65)
Diabetes mellitus (including NODAT)		2.02 (1.28–3.19)	2.82 (1.77–4.92)
Post-transplant ACEI/ARB Use			0.20 (0.13–0.32)
Post-transplant			0.41 (0.27–0.63)
Beta-blocker use
Post-transplant statin use			0.33 (0.21–0.53)

Only demographic variables, including age, African American race and male gender (1st column). The second analysis added transplant and cardiovascular (CV) risk factors to the model (2nd column). The third model included the addition of medication interventions that showed potential protective effects (3rd column). CI, confidence interval; ACEI, angiotensin-converting enzyme inhibitor; ARB, angiotensin II receptor blocker; NODAT, new-onset diabetes mellitus after transplant.