Carlton J. Young

Ethnic and Gender Related Differences in the Risk of End-Stage Renal Disease After Living Kidney Donation

There is limited data pertaining to the risk of End Stage Renal Disease (ESRD) after living kidney donation. The Organ Procurement and Transplantation Network and the Center for Medicare and Medicaid Services databases were used to identify living kidney donors (LKDs) who subsequently developed ESRD and to calculate LKD ESRD rates. We found 126 cases of ESRD among 56 458 LKDs (0.22%) who donated during October 1, 1987–March 31, 2003. The overall LKD ESRD rate was 0.134 per 1000 years at risk, with an average duration of follow‐up of 9.8 years. ESRD rates for LKDs overall and for Black, White, male and female donors compared favorably to the ESRD incidence in the general population. The LKD ESRD rate was nearly five times higher for Blacks than for Whites and two times higher for males than females. However, these ethnic and gender‐related differences were similar to those previously reported for ESRD in the general population. Our findings do not show an increase in the risk of ESRD for LKDs and support the current practice of living kidney donation. Further research is needed to determine if improved donor screening or follow‐up will reduce the risk of postdonation ESRD.

Medial Fibrosis, Vascular Calcification, Intimal Hyperplasia, and Arteriovenous Fistula Maturation

BACKGROUND Arteriovenous fistulas (AVFs) for hemodialysis frequently fail to mature because of inadequate dilation or early stenosis. The pathogenesis of AVF nonmaturation may be related to pre-existing vascular pathologic states: medial fibrosis or microcalcification may limit arterial dilation, and intimal hyperplasia may cause stenosis. STUDY DESIGN Observational study. SETTING & PARTICIPANTS Patients with chronic kidney disease (N = 50) undergoing AVF placement. PREDICTORS Medial fibrosis, microcalcification, and intimal hyperplasia in arteries and veins obtained during AVF creation. OUTCOME & MEASUREMENTS AVF nonmaturation. RESULTS AVF nonmaturation occurred in 38% of patients despite attempted salvage procedures. Preoperative arterial diameter was associated with upper-arm AVF maturation (P = 0.007). Medial fibrosis was similar in patients with nonmaturing and mature AVFs (60% ± 14% vs 66% ± 13%; P = 0.2). AVF nonmaturation was not associated with patient age or diabetes, although both variables were associated significantly with severe medial fibrosis. Conversely, AVF nonmaturation was higher in women than men despite similar medial fibrosis in both sexes. Arterial microcalcification (assessed semiquantitatively) tended to be associated with AVF nonmaturation (1.3 ± 0.8 vs 0.9 ± 0.8; P = 0.08). None of the arteries or veins obtained at AVF creation had intimal hyperplasia. However, repeated venous samples obtained in 6 patients during surgical revision of an immature AVF showed venous neointimal hyperplasia. LIMITATIONS Single-center study. CONCLUSION Medial fibrosis and microcalcification are frequent in arteries used to create AVFs, but do not explain AVF nonmaturation. Unlike previous studies, intimal hyperplasia was not present at baseline, but developed de novo in nonmaturing AVFs.

Outcomes of Brachiocephalic Fistulas, Transposed Brachiobasilic Fistulas, and Upper Arm Grafts

BACKGROUND AND OBJECTIVES An upper arm vascular access is often placed in patients with a failed forearm fistula or with vessels unsuitable for a forearm fistula. The aim of this study was to compare the outcomes of three upper arm access types: brachiocephalic fistulas, transposed brachiobasilic fistulas, and grafts. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS A prospective, computerized access database was queried retrospectively to identify the clinical outcomes of upper arm accesses placed in 678 patients at a large dialysis center, including 322 brachiocephalic fistulas, 67 brachiobasilic fistulas, and 289 grafts. RESULTS Primary access failures were less common for brachiobasilic fistulas and grafts compared with brachiocephalic fistulas (18%, 15%, and 38%; hazard ratio of brachiocephalic fistulas versus brachiobasilic fistulas 2.76; 95% confidence interval 1.41 to 5.38; P < 0.003). For the subset of patients receiving a brachiocephalic fistula, a multiple variable logistic regression analysis including age, sex, race, diabetes, coronary artery disease, peripheral vascular disease, cerebrovascular disease, prior access, surgeon, arterial diameter, and venous diameter found that only vascular diameters predicted primary failure (P < 0.001). When primary failures were excluded, cumulative access survival was similar for brachiobasilic and brachiocephalic fistulas, but superior to that of grafts. Total access interventions per year were lower for brachiobasilic and brachiocephalic fistulas than for grafts (0.84, 0.82, and 1.87, respectively, P < 0.001). CONCLUSIONS Transposed brachiobasilic fistulas may be preferred, due to (1) a lower primary failure rate (similar to grafts), and (2) a lower intervention rate (similar to brachiocephalic fistulas). However, this advantage must be balanced against the more complex surgery.

African Americans and Renal Transplantation: Disproportionate Need, Limited Access, and Impaired Outcomes

Background: Renal transplantation is the therapy of choice for patients with end‐stage renal disease (ESRD). However, African Americans’ (AA) access to this modality is not commensurate with that of other races. This imbalance, coupled with AA disproportionately representing those with ESRD, has kept AA disadvantaged compared with other races, especially whites. Methods: We reviewed published reports that examined the connection between race and the incidence of chronic renal failure, access to optimal therapy, and outcomes of renal transplantation. Results: The incidence of ESRD in AA is 4 times greater than in whites, but AA remain less likely than whites to be referred for or undergo renal transplantation. Also, AA are at greater risk than whites to experience premature graft failure. Conclusions: ESRD management has improved dramatically with the advent of successful renal transplantation. However, AA remain significantly disadvantaged in both access and outcomes compared with whites. Further evaluation of underlying causes and development of specific remedies is warranted.

Access and Outcomes Among Minority Transplant Patients, 1999–2008, with a Focus on Determinants of Kidney Graft Survival

Coincident with an increasing national interest in equitable health care, a number of studies have described disparities in access to solid organ transplantation for minority patients. In contrast, relatively little is known about differences in posttransplant outcomes between patients of specific racial and ethnic populations. In this paper, we review trends in access to solid organ transplantation and posttransplant outcomes by organ type, race and ethnicity. In addition, we present an analysis of categories of factors that contribute to the racial/ethnic variation seen in kidney transplant outcomes. Disparities in minority access to transplantation among wait‐listed candidates are improving, but persist for those awaiting kidney, simultaneous kidney and pancreas and intestine transplantation. In general, graft and patient survival among recipients of solid organ transplants is highest for Asians and Hispanic/Latinos, intermediate for whites and lowest for African Americans. Although much of the difference in outcomes between racial/ethnic groups can be accounted for by adjusting for patient characteristics, important observed differences remain. Age and duration of pretransplant dialysis exposure emerge as the most important determinants of survival in an investigation of the relative impact of center‐related versus patient‐related variables on kidney graft outcomes.

Improved outcomes in cadaveric renal allografts with pulsatile preservation

Background: Early immunologic and non‐immunologic injury of renal allografts adversely affects long‐term graft survival. Some degree of preservation injury is inevitable in cadaveric renal transplantation, and, with the reduction in early acute rejection, this non‐immunologic injury has assumed a greater relative importance. Optimal graft preservation will maximize the chances of early graft function and long‐term graft survival, but the best method of preservation – pulsatile perfusion (PP) versus cold storage (CS) – is debated. 
Methods: Primary cadaveric kidney recipients from January 1990 through December 1995 were evaluated. The effects of implantation warm ischemic time (WIT) (≤20 min, 21–40 min, or >40 min) and total ischemic time (TIT) (< or ≥20 h) on death‐censored graft survival were compared between kidneys preserved by PP versus those preserved by CS. The effect of preservation method on delayed graft function (DGF) was also examined. 
Results: There were 568 PP kidneys and 268 CS kidneys. Overall death‐censored graft survival was not significantly different between groups, despite worse donor and recipient characteristics in the PP group. CS kidneys with an implantation WIT >40 min had worse graft survival than those with <40 min (p=0.0004). Survival of PP kidneys and those transplanted into 2 DR‐matched recipients was not affected by longer implantation WIT. Longer TIT did not impact survival. DGF was more likely after CS preservation (20.2% versus 8.8%, p=0.001). 
Conclusions: Preservation with PP improves early graft function and lessens the adverse effect of increased warm ischemia in cadaveric renal transplantation. This method is likely associated with less preservation injury and/or increases the threshold for injury from other sources and is superior to CS.

Pretransplant status and patient survival following liver transplantation

The current liver allocation system has been criticized, since available organs go to those who are the most critically ill. These recipients have the poorest overall survival. Identification of pretransplant risk factors for mortality would allow better allocation of donor livers. This study was a retrospective analysis of pretransplant clinical and laboratory parameters and subsequent postoperative liver transplant mortality to identify high-risk subgroups. Of 347 consecutive consecutive primary liver transplant recipients, 59 (17%) met United Network for Organ Sharing (UNOS) criteria for status 4. Pretransplant factors included liver function, coagulation, albumin and ammonia levels, renal function, the presence of ascites, and etiology of liver disease. Overall 1-year patient survival was significantly worse for the status 4 recipients (89.0% vs. 67.7%; P = 0.01). In a univariate analysis of pretransplant risk factors for all recipients, elevated creatinine (P = 0.008) and ammonia (P = 0.009), and UNOS status 4 (P = 0.01) significantly affected postoperative survival. In multivariate analysis of pretransplant risk factors for all recipients, elevated creatinine (P = 0.003) was the only factor to significantly affect postoperative survival. In UNOS status 4 patients, univariate analysis of pretransplant risk factors and their influence on patient survival demonstrated that prolonged coagulation partial thromboplastin time (P = 0.04) and a higher grade of encephalopathy (P = 0.02) significantly affected postoperative survival. Advanced encephalopathy (P = 0.009) and prolonged partial thromboplastin time (P = 0.01) were the only significant risk factors by multivariate analysis in status 4 patients. In status 4 and non-status 4 patients, we identified risk factors that adversely affected patient survival, but their predictive power was insufficient to deny transplantation. Despite the higher mortality in status 4 recipients, their long-term survival is only slightly worse than that of non-status 4 patients. Until better predictors of survival are ascertained, our data do not support limiting the use of donor livers in UNOS status 4 recipients.

Systolic Dysfunction Portends Increased Mortality among Those Waiting for Renal Transplant

Individuals waiting for a renal transplant experience excessive cardiovascular mortality, which is not fully explained by the prevalence of ischemic heart disease in this population. Overt heart failure is known to increase the mortality of patients with ESRD, but the impact of lesser degrees of ventricular systolic dysfunction is unknown. For examination of the association between left ventricular ejection fraction(LVEF) and mortality of renal transplant candidates, the records of 2718 patients evaluated for transplantation at one institution were reviewed. During 6355 patient-years (median 27 mo) of follow-up, 681 deaths occurred. Patients with systolic dysfunction (LVEF <or= 0.40) had significantly lower survival than those with higher systolic function (median 49 +/- 3.1 versus 72 +/- 4.0 mo; P 0.001) but had similar survival to patients with ischemia (48 +/- 2.5 mo). Multivariate modeling showed that those with systolic dysfunction were nearly twice as likely to die as those with normal systolic function, adjusted for risk factors including diabetes, left ventricular hypertrophy, and ischemia (adjusted hazard ratio 1.7; 95%confidence interval 1.43 to 2.07). In addition, a graded, reverse association between LVEF and mortality was identified. In conclusion, systolic dysfunction is strongly associated with mortality, in a graded manner, in renal transplant candidates.

African American living-kidney donors should be screened for apol1 risk alleles

The adjusted rate of end-stage kidney disease (ESKD) among African Americans is markedly increased relative to European Americans. African Americans are overrepresented on the kidney transplantation waiting list and experience longer wait times. In aggregate, these pressures drive recommendations for living donor transplantation. Genovese et al. recently implicated the APOL1 gene in ESKD risk among African Americans (Genovese et al. Science 2010; 329: 841). The presence of two APOL1 risk alleles doubles the relative risk for ESKD; moreover, the alleles are prevalent among African Americans. We propose a strategy for screening for the presence of APOL1 risk alleles among African American living kidney donors and for living-related donors for African American recipients.

Preoperative Venous Intimal Hyperplasia, Postoperative Arteriovenous Fistula Stenosis, and Clinical Fistula Outcomes

BACKGROUND AND OBJECTIVES Arteriovenous fistulas often fail to mature, and nonmaturation has been attributed to postoperative stenosis caused by aggressive neointimal hyperplasia. Preexisting intimal hyperplasia in the native veins of uremic patients may predispose to postoperative arteriovenous fistula stenosis and arteriovenous fistula nonmaturation. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS This work explored the relationship between preexisting venous intimal hyperplasia, postoperative arteriovenous fistula stenosis, and clinical arteriovenous fistula outcomes in 145 patients. Venous specimens obtained during arteriovenous fistula creation were quantified for maximal intimal thickness (median thickness=22.3 μm). Postoperative ultrasounds at 4-6 weeks were evaluated for arteriovenous fistula stenosis. Arteriovenous fistula maturation within 6 months of creation was determined clinically. RESULTS Postoperative arteriovenous fistula stenosis was equally frequent in patients with preexisting venous intimal hyperplasia (thickness>22.3 μm) and patients without hyperplasia (46% versus 53%; P=0.49). Arteriovenous fistula nonmaturation occurred in 30% of patients with postoperative stenosis versus 7% of those patients without stenosis (hazard ratio, 4.33; 95% confidence interval, 1.55 to 12.06; P=0.001). The annual frequency of interventions to maintain arteriovenous fistula patency for dialysis after maturation was higher in patients with postoperative stenosis than patients without stenosis (0.83 [95% confidence interval, 0.58 to 1.14] versus 0.42 [95% confidence interval, 0.28 to 0.62]; P=0.008). CONCLUSIONS Preexisting venous intimal hyperplasia does not predispose to postoperative arteriovenous fistula stenosis. Postoperative arteriovenous fistula stenosis is associated with a higher arteriovenous fistula nonmaturation rate. Arteriovenous fistulas with hemodynamically significant stenosis frequently mature without an intervention. Postoperative arteriovenous fistula stenosis is associated with an increased frequency of interventions to maintain long-term arteriovenous fistula patency after maturation.