Effect of Replacing Race With Apolipoprotein L1 Genotype in Calculation of Kidney Donor Risk Index.

Renal allografts from deceased African American donors with two apolipoprotein L1 gene (APOL1) renal-risk variants fail sooner than kidneys from donors with fewer variants. The Kidney Donor Risk Index (KDRI) was developed to evaluate organ offers by predicting allograft longevity and includes African American race as a risk factor. Substituting APOL1 genotype for race may refine the KDRI. For 622 deceased African American kidney donors, we applied a 10-fold cross-validation approach to estimate contribution of APOL1 variants to a revised KDRI. Cross-validation was repeated 10 000 times to generate distribution of effect size associated with APOL1 genotype. Average effect size was used to derive the revised KDRI weighting. Mean current-KDRI score for all donors was 1.4930 versus mean revised-KDRI score 1.2518 for 529 donors with no or one variant and 1.8527 for 93 donors with two variants. Original and revised KDRIs had comparable survival prediction errors after transplantation, but the spread in Kidney Donor Profile Index based on presence or absence of two APOL1 variants was 37 percentage points. Replacing donor race with APOL1 genotype in KDRI better defines risk associated with kidneys transplanted from deceased African American donors, substantially improves KDRI score for 85-90% of kidneys offered, and enhances the link between donor quality and recipient need.

Apolipoprotein L1 gene variants in deceased organ donors are associated with renal allograft failure.

Apolipoprotein L1 gene (APOL1) nephropathy variants in African American deceased kidney donors were associated with shorter renal allograft survival in a prior single-center report. APOL1 G1 and G2 variants were genotyped in newly accrued DNA samples from African American deceased donors of kidneys recovered and/or transplanted in Alabama and North Carolina. APOL1 genotypes and allograft outcomes in subsequent transplants from 55 U.S. centers were linked, adjusting for age, sex and race/ethnicity of recipients, HLA match, cold ischemia time, panel reactive antibody levels, and donor type. For 221 transplantations from kidneys recovered in Alabama, there was a statistical trend toward shorter allograft survival in recipients of two-APOL1-nephropathy-variant kidneys (hazard ratio [HR] 2.71; p = 0.06). For all 675 kidneys transplanted from donors at both centers, APOL1 genotype (HR 2.26; p = 0.001) and African American recipient race/ethnicity (HR 1.60; p = 0.03) were associated with allograft failure. Kidneys from African American deceased donors with two APOL1 nephropathy variants reproducibly associate with higher risk for allograft failure after transplantation. These findings warrant consideration of rapidly genotyping deceased African American kidney donors for APOL1 risk variants at organ recovery and incorporation of results into allocation and informed-consent processes.

The APOL1 gene and allograft survival after kidney transplantation.

Coding variants in the apolipoprotein L1 gene (APOL1) are strongly associated with nephropathy in African Americans (AAs). The effect of transplanting kidneys from AA donors with two APOL1 nephropathy risk variants is unknown. APOL1 risk variants were genotyped in 106 AA deceased organ donors and graft survival assessed in 136 resultant kidney transplants. Cox-proportional hazard models tested for association between time to graft failure and donor APOL1 genotypes. The mean follow-up was 26.4 ± 21.8 months. Twenty-two of 136 transplanted kidneys (16%) were from donors with two APOL1 nephropathy risk variants. Twenty-five grafts failed; eight (32%) had two APOL1 risk variants. A multivariate model accounting for donor APOL1 genotype, overall African ancestry, expanded criteria donation, recipient age and gender, HLA mismatch, CIT and PRA revealed that graft survival was significantly shorter in donor kidneys with two APOL1 risk variants (hazard ratio [HR] 3.84; p = 0.008) and higher HLA mismatch (HR 1.52; p = 0.03), but not for overall African ancestry excluding APOL1. Kidneys from AA deceased donors harboring two APOL1 risk variants failed more rapidly after renal transplantation than those with zero or one risk variants. If replicated, APOL1 genotyping could improve the donor selection process and maximize long-term renal allograft survival.

Donor-recipient relationships in African American vs. Caucasian live kidney donors.

PURPOSE: The purpose of the study was to characterize differences in donor and recipient relationships between African American (AA) and Caucasian living kidney donors. METHODS: Data from all successful living kidney donors at a single institution between 1991 and 2009 were reviewed. Relationships between donor and recipient were categorized and between-group comparisons performed. RESULTS: The study sample consisted of 73 (18%) AA and 324 Caucasian living kidney donors. The distribution of donor-recipient relationships differed significantly between AA and Caucasians. AA donors were more likely to be related to the recipient (88% vs. 74%, p = 0.007) than Caucasians. AA donors were more likely to participate in child to parent donation and were less likely to participate in parent to child donation or to donate to unrelated individuals. Sibling and spousal donations were similar in both groups. Caucasian donors were more likely to be unrelated to the recipient than AA donors. CONCLUSIONS: Differences exist in donor-recipient relationships between AA and Caucasian living kidney donors. Future studies exploring cultural differences and family dynamics may provide targeted recruitment strategies for AA and Caucasian living kidney donors. Living unrelated kidney transplantation appears to be a potential growth area for living kidney donation in AA.

Short-term renal outcomes in African American and Caucasian donors following live kidney donation.

INTRODUCTION: Although African Americans (AA) are considered higher risk kidney donors than Caucasians, limited data are available regarding outcomes of AA donors. METHODS: We performed a single-center retrospective review of all kidney donors from 1993 to 2007 and evaluated race/ethnic differences in post-donation changes in renal function, incident proteinuria, and systolic blood pressure (SBP) using linear mixed models. RESULTS: A total of 336 kidney donors (63 AA, 263 Caucasian, 10 other) were evaluated. Before donation, AA had higher serum creatinine concentrations, estimated glomerular filtration rate (GFR) values, and SBP levels than Caucasians. No significant changes in SBP or renal function were observed between the two groups within the first year after donation, although results were limited by incomplete follow-up. CONCLUSION: AA had higher pre-donation serum creatinine, GFR, and SBP values compared to Caucasians; however, the degree of change in renal function and blood pressure did not differ between groups following kidney donation. Although long-term studies are needed, our study suggests that AA and Caucasians experience similar short-term consequences after donation. The incomplete data available on donor outcomes in our center and in prior publications also indicates a global need to implement systems for structured follow-up of live kidney donors.

Potential donor-recipient MYH9 genotype interactions in posttransplant nephrotic syndrome after pediatric kidney transplantation.

Recurrence of focal segmental glomerulosclerosis (FSGS) with nephrotic syndrome is relatively common after kidney transplantation in young recipients whose predialysis course consists of heavy proteinuria, hypertension and subacute loss of kidney function. The gene(s) mediating this effect remain unknown. We report an unusual circumstance where kidneys recovered from a deceased African American male donor with MYH9-related occult FSGS (risk variants in seven of eight MYH9 E1 haplotype single nucleotide polymorphisms) were transplanted into an African American male child with risk variants in four MYH9 E1 risk variants and a European American female teenager with two MYH9 E1 risk variants. Fulminant nephrotic syndrome rapidly developed in the African American recipient, whereas the European American had an uneventful posttransplant course. The kidney donor lacked significant proteinuria at the time of organ procurement. This scenario suggests that donor-recipient interactions in MYH9, as well as other gene-gene and gene-environment interactions, may lead to recurrent nephrotic syndrome after renal transplantation. The impact of transplanting kidneys from donors with multiple MYH9 risk alleles into recipients with similar genetic background at high risk for recurrent kidney disease needs to be determined.

Impact of race and gender on live kidney donation.

BACKGROUND: African Americans (AA) and women are less likely to receive a live kidney donor (LKD) transplant than Caucasians or men. Reasons for non-donation are poorly understood. METHODS: A retrospective review of 541 unsuccessful LKD was performed to explore reasons for non-donation and to assess for racial and/or gender differences. RESULTS: We identified 138 AA and 385 Caucasian subjects who volunteered but did not successfully donate. Females (58.2%) were more likely to be excluded than males due to reduced renal function (glomerular filtration rate < 85 mL/min, 7.9% vs. 0.9%, p < 0.0001) or failure to complete the evaluation (6.4% vs. 1.8%, p = 0.01). AA were more commonly excluded due to obesity (body mass index >or= 32 kg/m(2); 30.4% AA vs. 16.6% Caucasian, p = 0.0005) or failure to complete the evaluation (12.3% AA vs. 1.8% Caucasian, p < 0.0001) whereas Caucasians were more often excluded due to kidney stones (1.5% AA vs. 7.3% Caucasian, p = 0.01). CONCLUSIONS: Significantly different reasons for exclusion of LKD exist between potential Caucasian and AA LKD, particularly among women. Among the differences that we observed are potentially modifiable barriers to donation including obesity and failure to complete the donor evaluation. A further understanding of these barriers may help point to strategies for more effective recruitment and successful LKD.

Outcomes of extended donors in pancreatic transplantation with portal-enteric drainage.

OBJECTIVE: Limited data are available on extended (EX) donor criteria in pancreatic transplantation (PTX). METHODS: This retrospective study from February 2007 through April 2007 compared 2 cohorts of simultaneous kidney-pancreas transplantations (SKPT): the first from EX donors, which were defined as age <10 years or > or =45 years, or donation after cardiac death [DCD]), and the second from conventional (CONV) donors. RESULTS: Among 79 SKPT, 19 (24%) were from EX donors (12 older than age 45 [mean age, 50.2 years], 3 pediatric donors <10, and 4 DCD donors) and the remaining 60 SKPT from CONV donors. The mean donor age was higher in EX than CONV donors (38 vs 25 years, P < .05). There were no other differences between the 2 cohorts. With a similar median follow-up of 29 months, patient, kidney and pancreatic graft survival rates were 89%, 89%, and 79%, for the EX, whereas corresponding outcomes for CONV donors were 93%, 87%, and 80%, respectively (all P = NS). The incidences were similar for delayed kidney graft function (5% in each group), early pancreatic graft loss due to thrombosis (5% EX vs 8% CONV donors), acute rejection (16% EX vs 18% CONV donors), surgical complications, and infections. There were no significant differences in 1-year mean serum creatinine (1.4 mg/dL in each group) or glycohemoglobin (5.2% vs 5.5%) levels between the EX and CONV donor groups, respectively. CONCLUSION: Short-term outcomes among SKPT from selected EX donors were comparable to CONV donors. Donors at the extremes of age and DCD donors may represent underused resources in SKPT.

Analysis of bacteremia after pancreatic transplantation with enteric drainage.

OBJECTIVE: The objective of this study was to review the incidence, risk factors, and impact of bacteremia after pancreas transplantation (PTX). METHODS: We performed a retrospective analysis of consecutive simultaneous kidney-pancreas transplantations (SKPTs) and solitary PTXs from January 2002 through April 2007. Positive blood cultures were correlated with other coexisting infections and parameters. RESULTS: One hundred ten PTXs with enteric drainage included 80 SKPTs and 30 solitary PTXs. Mean follow-up was 32 months. Bacteremia occurred in 29 (26%) patients with 5 (17%) being recurrent; it was seen during the first month after transplantation in 13 (12%), between 1 and 3 months in 12 (11%), between 3 and 12 months in 3 (3%), and after the first year in 3 cases (3%). Typical organisms were as follows: MRSE, MSSE, Klebsiella, Escherichia coli, vancomycin-resistant enterococci (VRE), and Acinetobacteri. Bacteremia was associated with coexisting site infection in 20 cases (69%): deep abdominal wound (31%); line (31%); urinary tract (34%); and pulmonary (7%). Similar bacterial species in blood and a coexisting site occurred in 15 cases (52%). No correlation was seen with cytomegalovirus (CMV) infections. In the first year, bacteremia was associated with more acute rejection episodes (32% vs 17%; P = .09), surgical complications (54% vs 42%; P = .267), mortality (11% vs 4%; P = .15), and death-censored pancreatic (14% vs 9%; P = .39) and kidney (4% vs 0; P = .08) graft loss. Fewer patients with bacteremia received alemtuzumab compared with rATG induction (14% vs 39%; P = .04). CONCLUSIONS: Bacteremias were common within 3 months of PTX. A significant number (39%) were multidrug resistant. The majority were accompanied by abdominal, urinary, or line infections. Bacteremias were associated with slightly higher incidences of rejection, mortality, and graft loss.

Do pretransplant C-peptide levels influence outcomes in simultaneous kidney-pancreas transplantation?

OBJECTIVE: To analyze outcomes in simultaneous kidney-pancreas transplantation (SKPT) recipients who retain C-peptide production at the time of SKPT. METHODS: This retrospective analysis of SKPTs from January 2002 through January 2007 compared outcomes between patients with absent or low C-peptide levels (<2.0 ng/mL, group A) with those having levels > or =2.0 ng/mL (group B). RESULTS: Among 74 SKPTs, 67 were in group A and seven in group B (mean C-peptide level 5.7 ng/mL). During transplantation, group B subjects were older (mean age 51 vs 41 years, P = .006); showed a later age of onset of diabetes (median 35 vs 13 years, P = .0001); weighed more (median 77 vs 66 kg, P = .24); had a greater proportion of African-Americans (57% vs 13%, P = .004); and had a longer pretransplant duration of dialysis (median 40 vs 14 months, P = .14). With similar median follow-up of 40 months, death-censored kidney (95% group A vs 100% group B, P = NS) and pancreas (87% group A vs 100% group B, P = NS) graft survival rates were similar, but patient survival (94% group A vs 71% group B, P = .03) was greater in group A. At 1-year follow-up, there were no significant differences in rejection episodes, surgical complications, infections, readmissions, hemoglobin A1C or C-peptide levels, serum creatinine, or MDRD GFR levels. CONCLUSIONS: Diabetic patients with measurable C-peptide levels before transplant were older, overweight, more frequently African-American and had a later age of onset of diabetes, longer duration of pretransplant dialysis, and reduced patient survival compared to insulinopenic patients undergoing SKPT. The other outcomes were similar.

Characteristics of sudden death in hemodialysis patients.

Hemodialysis (HD) is an intermittent procedure during which large fluid and electrolyte shifts occur. We hypothesized that sudden death occurrences in HD patients are related to the timing of HD, and that they occur more frequently in the 12 h period starting with dialysis and in the 12 h period at the end of the dialysis-free weekend interval. In a retrospective study, 228 patient deaths were screened to determine if they met the criteria for sudden death. Information was obtained from clinic charts, dialysis center records, and interview of witnesses of the death event. There were 80 HD patients who met the criteria for sudden death. A bimodal distribution of death occurrences was present, with a 1.7-fold increased death risk occurring in the 12 h period starting with the dialysis procedure and a threefold increased risk of death in the 12 h before HD at the end of the weekend interval (P=0.011). Patients with sudden death had a high prevalence of congestive heart failure and coronary artery disease. Only 40% of patients experiencing sudden death were receiving beta-blockers, and the prior monthly serum potassium value was less than 4 mEq/l in 25%. Sudden death is temporally related to the HD procedure. Every other day HD could be beneficial in preventing sudden death. Careful attention to the usage of beta-blockers and to the maintenance of normal serum potassium values is indicated in HD patients at risk for sudden death.