Faculty Bibliography

BACKGROUND:Tertiary hyperparathyroidism after kidney transplantation has been associated with graft dysfunction, cardiovascular morbidity, and osteopenia; however, its true prevalence is unclear. The objective of our study was to evaluate the prevalence of and risk factors for tertiary hyperparathyroidism. METHODS:A prospective cohort of 849 adult kidney transplantation recipients (December 2008-February 2020) was used to estimate the prevalence of hyperparathyroidism 1-year post-kidney transplant. Tertiary hyperparathyroidism was defined as hypercalcemia (≥10mg/dL) and hyperparathyroidism (parathyroid hormone≥70pg/mL) 1-year post-kidney transplantation. Modified Poisson regression models were used to evaluate risk factors associated with the development of both persistent hyperparathyroidism and tertiary hyperparathyroidism. RESULTS:Among kidney transplantation recipients, 524 (61.7%) had persistent hyperparathyroidism and 182 (21.5%) had tertiary hyperparathyroidism at 1-year post-kidney transplantation. Calcimimetic use before kidney transplantation was associated with 1.30-fold higher risk of persistent hyperparathyroidism (adjusted prevalence ratio = 1.30, 95% CI: 1.12-1.51) and 1.84-fold higher risk of tertiary hyperparathyroidism (adjusted prevalence ratio = 1.84, 95% CI: 1.25-2.72). Pre-kidney transplantation parathyroid hormone ≥300 pg/mL was associated with 1.49-fold higher risk of persistent hyperparathyroidism (adjusted prevalence ratio = 1.49, 95% CI = 1.19-1.85) and 2.21-fold higher risk of tertiary hyperparathyroidism (adjusted prevalence ratio = 2.21, 95% CI = 1.25-3.90). Pre-kidney transplantation tertiary hyperparathyroidism was associated with an increased risk of post-kidney transplantation tertiary hyperparathyroidism (adjusted prevalence ratio = 1.71, 95% CI = 1.29-2.27), but not persistent hyperparathyroidism. Furthermore, 73.0% of patients with persistent hyperparathyroidism and 61.5% with tertiary hyperparathyroidism did not receive any treatment at 1-year post-kidney transplantation. CONCLUSION/CONCLUSIONS:Persistent hyperparathyroidism affected 61.7% and tertiary hyperparathyroidism affected 21.5% of kidney transplantation recipients; however, the majority of patients were not treated. Pre-kidney transplantation parathyroid hormone levels ≥300pg/mL and the use of calcimimetics are associated with the development of tertiary hyperparathyroidism. These findings encourage the re-evaluation of recommended pre-kidney transplantation parathyroid hormone thresholds and reconsideration of pre-kidney transplantation secondary hyperparathyroidism treatments to avoid the adverse sequelae of tertiary hyperparathyroidism in kidney transplantation recipients.

Background/UNASSIGNED:The development of cytomegalovirus (CMV) infection after kidney transplant remains a significant cause of posttransplant morbidity, graft loss, and mortality. Despite appropriate antiviral therapy, recipients without previous CMV exposure can currently be allocated a kidney from a donor with previous CMV infection (D+R-) which carries the greatest risk of posttransplant CMV infection and associated complications. Preferential placement of CMV D- organs in negative recipients (R-) has been shown to reduce the risk of viral infection and associated complications. Methods/UNASSIGNED:To assess the long-term survival and economic benefits of allocation policy reforms, a decision analytic model was constructed to compare receipt of CMV D- with CMV D+ organ in CMV R- recipients using data from transplant registry, Medicare claims, and pharmaceutical costs. Results/UNASSIGNED:For CMV R- patients, receipt of a CMV D- organ was associated with greater average survival (14.3 vs 12.6 years), superior quality-adjusted life years (12.6 vs 9.8), and lower costs ($529 512 vs $542 963). One-way sensitivity analysis demonstrated a survival advantage for patients waiting as long as 30 months for a CMV D- kidney. Conclusions/UNASSIGNED:Altering national allocation policy to preferentially offer CMV D- organs to CMV R- recipients could improve survival and lower costs after transplant if appropriately implemented.

Donor/recipient incompatibility in kidney transplantation classically refers to ABO/HLA-incompatibility. Kidney paired donation (KPD) was historically established to circumvent ABO/HLA-incompatibility, with the goal of identifying ABO/HLA-compatible matches. However, there is a broad range of donor factors known to impact recipient outcomes beyond ABO/HLA-incompatibility, such as age and weight, and quantitative tools are now available to empirically compare potential living donors across many of these factors, such as the living donor kidney donor profile index (LKDPI). Moreover, the detrimental impact of mismatch at other HLA antigens (such as DQ) and epitope mismatching on posttransplant outcomes has become increasingly recognized. Thus, it is time for a new paradigm of incompatibility that considers all of these risks factors together in assessing donor/recipient compatibility and the potential utility for KPD. Under this new paradigm of incompatibility, we show how the LKDPI and other tools can be used to identify donor/recipient incompatibilities that could be improved through KPD, even for those with a traditionally "compatible" living donor.

Status 1A liver transplant candidates are given the highest medical priority for the allocation of deceased donor livers. Organ Procurement and Transplantation Network (OPTN) policy requires physicians to certify that a candidate has a life expectancy without a transplant of less than 7 days for that candidate to be given status 1A. Additionally, candidates receiving status 1A must have one of six medical conditions listed in policy. Using Scientific Registry of Transplant Recipients data from all prevalent liver transplant candidates from 2010 to 2020, we used a bias-corrected Kaplan-Meier model to calculate the survival of status 1A candidates and to determine their life expectancy without a transplant. We found that status 1A candidates have a life expectancy without a transplant of 24 (95% CI 20-46) days-over three times longer than what policy requires for status 1A designation. We repeated the analysis for subgroups of status 1A candidates based on the medical conditions that grant status 1A. We found that none of these subgroups met the life expectancy requirement. Harmonizing OPTN policy with observed data would sustain the integrity of the allocation process.

Acuity circles (AC), the new liver allocation system, was implemented on February 4, 2020. Difference-in-differences analyses estimated the effect of AC on adjusted deceased donor transplant and offer rates across Pediatric End-Stage Liver Disease (PELD) and Model for End-Stage Liver Disease (MELD) categories and types of exception statuses. The offer rates were the number of first offers, top 5 offers, and top 10 offers on the match run per person-year. Each analysis adjusted for candidate characteristics and only used active candidate time on the waiting list. The before-AC period was February 4, 2019, to February 3, 2020, and the after-AC period was February 4, 2020, to February 3, 2021. Candidates with PELD/MELD scores 29 to 32 and PELD/MELD scores 33 to 36 had higher transplant rates than candidates with PELD/MELD scores 15 to 28 after AC compared with before AC (transplant rate ratios: PELD/MELD scores 29-32, _2.34 3.32_4.71 ; PELD/MELD scores 33-36, _1.70 2.51_3.71 ). Candidates with PELD/MELD scores 29 or higher had higher offer rates than candidates with PELD/MELD scores 15 to 28, and candidates with PELD/MELD scores 29 to 32 had the largest difference (offer rate ratios [ORR]: first offers, _2.77 3.95_5.63 ; top 5 offers, _3.90 4.39_4.95 ; top 10 offers, _4.85 5.30_5.80 ). Candidates with exceptions had lower offer rates than candidates without exceptions for offers in the top 5 (ORR: hepatocellular carcinoma [HCC], _0.68 0.77_0.88 ; non-HCC, _0.73 0.81_0.89 ) and top 10 (ORR: HCC, _0.59 0.65_0.71 ; non-HCC, _0.69 0.75_0.81 ). Recipients with PELD/MELD scores 15 to 28 and an HCC exception received a larger proportion of donation after circulatory death (DCD) donors after AC than before AC, although the differences in the liver donor risk index were comparatively small. Thus, candidates with PELD/MELD scores 29 to 34 and no exceptions had better access to transplant after AC, and donor quality did not notably change beyond the proportion of DCD donors.

Increasing numbers of compatible pairs are choosing to enter paired exchange programs, but motivations, outcomes, and system-level effects of participation are not well described. Using a linkage of the Scientific Registry of Transplant Recipients and National Kidney Registry, we compared outcomes of traditional (originally incompatible) recipients to originally compatible recipients using the Kaplan-Meier method. We identified 154 compatible pairs. Most pairs sought to improve HLA matching. Compared to the original donor, actual donors were younger (39 vs. 50 years, p < .001), less often female (52% vs. 68%, p < .01), higher BMI (27 vs. 25 kg/m², p = .03), less frequently blood type O (36% vs. 80%, p < .001), and had higher eGFR (99 vs. 94 ml/min/1.73 m², p = .02), with a better LKDPI (median 7 vs. 22, p < .001). We observed no differences in graft failure or mortality. Compatible pairs made 280 additional transplants possible, many in highly sensitized recipients with long wait times. Compatible pair recipients derived several benefits from paired exchange, including better donor quality. Living donor pairs should receive counseling regarding all options available, including kidney paired donation. As more compatible pairs choose to enter exchange programs, consideration should be given to optimizing compatible pair and hard-to-transplant recipient outcomes.

BACKGROUND:Early steroid withdrawal (ESW) is a viable maintenance immunosuppression strategy in low-risk kidney transplant recipients. A low panel reactive antibody (PRA) may indicate low-risk condition amenable to ESW. We aimed to identify the threshold value of PRA above which ESW may pose additional risk, and to compare the association of ESW with transplant outcomes across PRA strata. METHODS:We studied 121,699 deceased-donor kidney-only recipients in 2002-2017 from SRTR. Using natural splines and ESW-PRA interaction terms, we explored how the associations of ESW with transplant outcomes change with increasing PRA values, and identified a threshold value for PRA. Then, we assessed whether PRA exceeding the threshold modified the associations of ESW with 1-year acute rejection, death-censored graft failure, and death. RESULTS:The association of ESW with acute rejection exacerbated rapidly when PRA exceeded 60. Among PRA≤60 recipients, ESW was associated with a minor increase in rejection (aOR=1.001.051.10) and with a tendency of decreased graft failure (aHR=0.910.971.03). However, among PRA>60 recipients, ESW was associated with a substantial increase in rejection (aOR=1.191.271.36; interaction p<0.001) and with a tendency of increased graft failure (aHR=0.981.081.20; interaction p=0.028). The association of ESW with death was similar between PRA strata (PRA≤60, aHR=0.910.961.01; and PRA>60, aHR=0.900.991.09; interaction p=0.5). CONCLUSIONS:Our findings show that the association of ESW with transplant outcomes is less favorable in recipients with higher PRA, especially those with PRA>60, suggesting a possible role of PRA in the risk assessment for ESW.

BACKGROUND:Organ transplantation from donors with HIV to recipients with HIV (HIV D+/R+) presents risks of donor-derived infections. Understanding clinical, immunologic, and virologic characteristics of HIV+ donors is critical for safety. METHODS:We performed a prospective study of donors with HIV-positive and HIV false-positive (FP) testing within the HOPE in Action studies of HIV D+/R+ transplantation (ClinicalTrials.gov NCT02602262; NCT03500315; NCT03734393). We compared clinical characteristics in HIV+ versus FP donors. We measured CD4+ T cells, HIV viral load (VL), drug resistance mutations (DRMs), co-receptor tropism, and serum antiretroviral therapy (ART) detection using mass spectrometry in HIV+ donors. RESULTS:Between 03/2016-03/2020, 92 donors (58 HIV+, 34 FP), representing 98.9% of all US HOPE donors during this period, donated 177 organs (131 kidney, 46 liver). Each year the number of donors increased. Prevalence of hepatitis B (16% vs. 0%), syphilis (16% vs. 0%), and cytomegalovirus (91% vs. 58%) was higher in HIV+ versus FP donors; hepatitis C viremia was similar (2% vs. 6%). Most HIV+ donors (71%) had known HIV diagnosis, of whom 90% were prescribed ART and 68% had VL<400 copies/mL. Median CD4 count was 194 cells/uL (IQR=77-331); median CD4% was 27.0 (IQR=16.8-36.1). Major HIV DRMs were detected in 42%, including non-nucleoside reverse transcriptase inhibitors (33%), integrase strand transfer inhibitor (INSTI, 4%), and multiclass (13%). Serum ART was detected in 46% and matched ART by history. CONCLUSION/CONCLUSIONS:Utilization of HIV+ donor organs is increasing. HIV DRMs are common, yet resistance that would compromise INSTI-based regimens is rare, which is reassuring regarding safety.