Faculty Bibliography

BACKGROUND:The burden of end-stage kidney disease (ESKD) and kidney transplant rates vary significantly across the United States. This study aims to examine the mismatch between ESKD burden and kidney transplant rates from a perspective of spatial epidemiology. METHODS:US Renal Data System data from 2015 to 2017 on incident ESKD and kidney transplants per 1000 incident ESKD cases was analyzed. Clustering of ESKD burden and kidney transplant rates at the county level was determined using local Moran's I and correlated to county health scores. Higher percentile county health scores indicated worse overall community health. RESULTS:Significant clusters of high-ESKD burden tended to coincide with clusters of low kidney transplant rates, and vice versa. The most common cluster type had high incident ESKD with low transplant rates (377 counties). Counties in these clusters had the lowest overall mean transplant rate (61.1), highest overall mean ESKD incidence (61.3), and highest mean county health scores percentile (80.9%, P <0.001 vs all other cluster types). By comparison, counties in clusters with low ESKD incidence and high transplant rates (n=359) had the highest mean transplant rate (110.6), the lowest mean ESKD incidence (28.9), and the lowest county health scores (20.2%). All comparisons to high-ESKD/low-transplant clusters were significant at P value <0.001. CONCLUSION:There was a significant mismatch between kidney transplant rates and ESKD burden, where areas with the greatest need had the lowest transplant rates. This pattern exacerbates pre-existing disparities, as disadvantaged high-ESKD regions already suffer from worse access to care and overall community health, as evidenced by the highest county health scores in the study.

BACKGROUND:Much of our understanding regarding geographic issues in transplantation is based on statistical techniques that do not formally account for geography and is based on obsolete boundaries such as donation service area. METHODS:We applied spatial epidemiological techniques to analyze liver-related mortality and access to liver transplant services at the county level using data from the Centers for Disease Control and Prevention and Scientific Registry of Transplant Recipients from 2010 to 2018. RESULTS:There was a significant negative spatial correlation between transplant rates and liver-related mortality at the county level (Moran's I, -0.319; P  = 0.001). Significant clusters were identified with high transplant rates and low liver-related mortality. Counties in geographic clusters with high ratios of liver transplants to liver-related deaths had more liver transplant centers within 150 nautical miles (6.7 versus 3.6 centers; P  < 0.001) compared with all other counties, as did counties in geographic clusters with high ratios of waitlist additions to liver-related deaths (8.5 versus 2.5 centers; P  < 0.001). The spatial correlation between waitlist mortality and overall liver-related mortality was positive (Moran's I, 0.060; P  = 0.001) but weaker. Several areas with high waitlist mortality had some of the lowest overall liver-related mortality in the country. CONCLUSIONS:These data suggest that high waitlist mortality and allocation model for end-stage liver disease do not necessarily correlate with decreased access to transplant, whereas local transplant center density is associated with better access to waitlisting and transplant.

BACKGROUND:Donation after cardiac death(DCD) has been proposed as an avenue to expand the liver donor pool. METHODS:We examined factors associated with nonrecovery of DCD livers using UNOS data from 2015 to 2019. RESULTS:There 265 non-recovered potential(NRP) DCD livers. Blood type AB (7.8% vs. 1.1%) and B (16.9% vs. 9.8%) were more frequent in the NRP versus actual donors (p < 0.001). The median driving time between donor hospital and transplant center was similar for NRP and actual donors (30.1 min vs. 30.0 min; p = 0.689), as was the percentage located within a transplant hospital (20.8% vs. 20.9%; p = 0.984).The donation service area(DSA) of a donor hospital explained 27.9% (p = 0.001) of the variability in whether a DCD liver was recovered. CONCLUSION:A number of potentially high quality DCD donor livers go unrecovered each year, which may be partially explained by donor blood type and variation in regional and DSA level practice patterns.

BACKGROUND:Community-level factors contribute to living donor kidney transplantation disparities but may also influence the interventions aimed to mitigate these disparities. The Living Donor Navigator Program was designed to separate the advocacy role from the patient in need of transplantation-friends/family are encouraged to participate as the patients' advocates to identify living donors, though some of the patients participate alone as self-advocates. Self-advocates have a lower living donor kidney transplantation likelihood compared to the patients with an advocate. We sought to evaluate the relationship between the patients' community-level vulnerability and living donor navigator self-advocacy as a surrogate for program fidelity. METHODS:This single-center, retrospective study included 110 Living Donor Navigator participants (April 2017-June 2019). Program fidelity was assessed using the participants' advocacy status. Measures of community vulnerability were obtained from the Centers for Disease Control and Prevention Social Vulnerability Index. Modified Poisson regression was used to evaluate the association between community-level vulnerability and living donor navigator self-advocacy. RESULTS:Of the 110 participants, 19% (n = 21) were self-advocates. For every 10% increase in community-level vulnerability, patients had 17% higher risk of self-advocacy (adjusted relative risk 1.17, 95% confidence interval: 1.03-1.32, P = .01). Living in areas with greater unemployment (adjusted relative risk: 1.18, 95% confidence interval: 1.04-1.33, P = .01), single-parent households (adjusted relative risk: 1.23, 95% confidence interval: 1.06-1.42, P = .006), minority population (adjusted relative risk: 1.30, 95% confidence interval: 1.04-1.55, P = .02), or no-vehicle households (adjusted relative risk: 1.17, 95% confidence interval: 1.02-1.35, P = .02) were associated with increased risk of self-advocacy. CONCLUSION:Having a greater community-level vulnerability was associated with poor Living Donor Navigator Program fidelity. The potential barriers identified using the Social Vulnerability Index may direct resource allocation and program refinement to optimize program fidelity and efficacy for all participants.

INTRODUCTION:Time-zero biopsies can detect donor-derived lesions at the time of kidney transplantation, but their utility in predicting long-term outcomes is unclear under the updated Kidney Allocation System. METHODS:We conducted a single-center retrospective cohort study of 272 consecutive post-reperfusion time-zero biopsies. We tested the hypothesis that abnormal time-zero histology is a strong indicator of donor quality that increases the precision of the kidney donor profile index (KDPI) score to predict long-term outcomes. RESULTS:We detected abnormal biopsies in 42% of the cohort, which were independently associated with a 1.2-fold increased hazard for a composite of acute rejection, allograft failure, and death after adjusting for clinical characteristics including KDPI. By Kaplan-Meier analysis, the relationship between abnormal time-zero histology and the composite endpoint was only significant in the subgroup of deceased donor kidney transplants with KDPI scores >35. Abnormal time-zero histology, particularly vascular intimal fibrosis and arteriolar hyalinosis scores, was independently associated with lower 12-month estimated GFR. CONCLUSION:In conclusion, abnormal time-zero histology is relatively common and identifies a group of kidney recipients at increased risk for worse long-term outcomes. Further studies are needed to determine the optimal patient population in which to deploy time-zero biopsies as an additional surveillance tool.

BACKGROUND:Third time liver transplantation is a technically demanding exercise with variable outcomes in single center series. There has been no national level description of survival following third time liver transplant in the US in the MELD era. METHODS:Third time liver transplants between March 1, 2002 and January 1, 2018 in the UNOS dataset were analyzed. RESULTS:Patient survival among the 240 third time liver transplant recipients in the study at 1, 3, 5, and 10 years (71.8%, 62.4%, 59.1%, 49.5%) was significantly worse compared to primary liver transplant (90.6%, 83.9%, 78.8%, 67.6%; p < 0.001) and retransplant (77.1%, 70.3%, 65.6%, 54.9%; p = 0.014). Recipients who were under 43 years old, not on dialysis, without diabetes, and over 1 month out from their second transplant had acceptable survival at 1, 3, 5, and 10 years (88.5%, 78.4%, 73.6%, 69.7%). CONCLUSIONS:While redo-redo transplant remains a challenging endeavor, appropriate patient selection can yield acceptable results.

BACKGROUND:Despite regulations mandating follow-up laboratory testing for living kidney donors, less than half of transplant centers are in compliance. We sought to understand barriers to follow-up testing from the donors' perspective. METHODS:We surveyed our center's living kidney donors. Binary logistic regression was used to assess factors associated with follow-up testing completion. RESULTS:Of 185 living kidney donors, 110 (59.4%) participated. Among them, 82 (74.5%) completed 6-month laboratory testing, 76 (69.1%) completed 12-month testing, 68 (61.8%) completed both, and 21 (19.0%) completed neither. Six-month testing completion was strongly associated with 12-month testing completion (OR 9.74, 95%CI: 2.23-42.50; p = .002). Those who disagreed with the statements, "Getting labs checked wasn't a priority for me," (OR for completing 6-month testing: 15.05, 95%CI: 3.70-61.18; p < .001; OR for completing 12-month testing: 5.85, 95%CI: 1.94-17.63; p = .002); and, "I forgot to get labs drawn [until I was reminded]" (OR for completing 6-month testing: 6.93, 95%CI: 1.59-30.08; p = .01; OR for completing 12-month testing: 6.55, 95%CI: 1.98-21.63; p = .002) were more likely to complete testing. CONCLUSIONS:To our knowledge, this is the only study providing perspective on donor insights regarding the need for follow-up testing post donation. Interventions to influence living donor attitudes toward follow-up testing may improve follow-up.

A radical solution is needed for the organ supply crisis, and the domestic pig is a promising organ source. In preparation for a clinical trial of xenotransplantation, we developed an in vivo pre-clinical human model to test safety and feasibility tenets established in animal models. After performance of a novel, prospective compatible crossmatch, we performed bilateral native nephrectomies in a human brain-dead decedent and subsequently transplanted two kidneys from a pig genetically engineered for human xenotransplantation. The decedent was hemodynamically stable through reperfusion, and vascular integrity was maintained despite the exposure of the xenografts to human blood pressure. No hyperacute rejection was observed, and the kidneys remained viable until termination 74 h later. No chimerism or transmission of porcine retroviruses was detected. Longitudinal biopsies revealed thrombotic microangiopathy that did not progress in severity, without evidence of cellular rejection or deposition of antibody or complement proteins. Although the xenografts produced variable amounts of urine, creatinine clearance did not recover. Whether renal recovery was impacted by the milieu of brain death and/or microvascular injury remains unknown. In summary, our study suggests that major barriers to human xenotransplantation have been surmounted and identifies where new knowledge is needed to optimize xenotransplantation outcomes in humans.

INTRODUCTION/BACKGROUND:The pediatric obesity epidemic is associated with early development of hepatic macrosteatosis, a hallmark of non-alcoholic fatty LI disease, which is thought to be more rapidly progressive in children than adults. Macrosteatosis in adult allografts is associated with allograft loss, but this has not been examined in pediatric donors. METHODS:We studied all pediatric potential whole LI donors (2005-2018) who had a LI biopsy in the SRTR (n = 862) and whose LI was transplanted (n = 862). Macrosteatosis was abstracted from biopsy reports and compared to values in the SRTR standard analytic file. Recipients of macrosteatotic pediatric allografts were matched 1:1 to recipients of non-macrosteatotic pediatric allografts by propensity score matching on donor/recipient variables. All-cause allograft loss was estimated via Kaplan-Meier analysis and Cox proportional hazards model. RESULTS:From 2005 to 2018, the proportion of pediatric donors (age ≥2 years) with obesity increased (14.8% to 21.7%; p < .001), as did the proportion of pediatric deceased whole LI-only donor allografts with macrosteatosis (n = 10 648; 1.8% to 3.9%; p < .001). The median degree of macrosteatosis among macrosteatotic donors was 10% (IQR 5-30). There were no significant differences in all-cause allograft loss between recipients of pediatric LI allografts with and without macrosteatosis at 90 days (p = .11) or 1 year (p = .14) post-transplant in Kaplan-Meier analysis or a Cox proportional hazards model (p > .05). CONCLUSION/CONCLUSIONS:Obese pediatric LI donors have increased over time and were more likely to have hepatic macrosteatosis; however, pediatric macrosteatosis did not appear to adversely affect recipient outcomes.