Faculty Bibliography

BACKGROUND:Organs from Public Health Service criteria (PHSC) donors, previously referred to as PHS infectious-risk donors, have historically been recovered but not used, traditionally referred to as "discard," at higher rates despite negligible risk to recipients. On March 1, 2021, the definition of PHSC donors narrowed to include only the subset of donors deemed to have meaningfully elevated risk in the current era of improved infectious disease testing. METHODS:Using Scientific Registry of Transplant Recipients data from May 1, 2019, to December 31, 2022, we compared rates of PHSC classification and nonutilization of PHSC organs before versus after the March 1, 2021, policy change among recovered decedents using the χ2 tests. We performed an adjusted interrupted time series analysis to examine kidney and liver recovery/nonuse (traditionally termed "discard") and kidney, liver, lung, and heart nonutilization (nonrecovery or recovery/nonuse) prepolicy versus postpolicy. RESULTS:PHSC classification dropped sharply from 24.5% prepolicy to 15.4% postpolicy (P < 0.001). Before the policy change, PHSC kidney recovery/nonuse, liver nonuse, lung nonuse, and heart nonuse were comparable to non-PHSC estimates (adjusted odds ratio: kidney = 0.981.061.14, P = 0.14; liver = 0.850.921.01, P = 0.07; lung = 0.910.991.08, P = 0.83; heart = 0.890.971.05, P = 0.47); following the policy change, PHSC kidney recovery/nonuse, liver nonuse, lung nonuse, and heart nonuse were lower than non-PHSC estimates (adjusted odds ratio: kidney = 0.770.840.91, P < 0.001; liver = 0.770.840.92, P < 0.001; lung = 0.740.810.90, P < 0.001; heart = 0.610.670.73, P < 0.001). CONCLUSIONS:Even though PHSC donors under the new definition are a narrower and theoretically riskier subpopulation than under the previous classification, PHSC status appears to be associated with a reduced risk of kidney and liver recovery/nonuse and nonutilization of all organs. Although historically PHSC organs have been underused, our findings demonstrate a notable shift toward increased PHSC organ utilization.

BACKGROUND:Kidney transplant recipients (KTRs) generate lower antibody responses to messenger RNA (mRNA)-based severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination, yet precise mechanisms for this poor response remain uncertain. One potential contributor is suboptimal spike antigen (sAg) translation and expression owing to transplant immunosuppression, which might lead to insufficient exposure to develop humoral and/or cellular immune responses. METHODS:Within a single-arm clinical trial, 65 KTRs underwent ultrasensitive plasma sAg testing before, and 3 and 14 days after, the third mRNA vaccine doses. Anti-SARS-CoV-2 spike antibodies (anti-receptor binding domain [anti-RBD]) were serially measured at 14 and 30 days post-vaccination. Associations between sAg detection and clinical factors were assessed. Day 30 anti-RBD titer was compared among those with versus without sAg expression using Wilcoxon rank sum testing. RESULTS:Overall, 16 (25%) KTRs were sAg positive (sAg+) after vaccination, peaking at day 3. Clinical and laboratory factors were broadly similar in sAg(+) versus sAg(-) KTRs. sAg(+) status was significantly negatively associated with day 30 anti-RBD response, with median (interquartile range) 10.8 (<0.4-338.3) U/mL if sAg(+) versus 709 (10.5-2309.5) U/mL if sAg(-) (i.e., 66-fold lower; p = .01). CONCLUSION/CONCLUSIONS:Inadequate plasma sAg does not likely drive poor antibody responses in KTRs, rather sAg detection implies insufficient immune response to rapidly clear vaccine antigen from blood. Other downstream mechanisms such as sAg trafficking and presentation should be explored.

Transplantation remains the gold-standard treatment for pediatric end-stage kidney disease. While living donor transplant is the preferred option for most pediatric patients, it is not the right choice for all. For those who have the option to choose between deceased donor and living donor transplantation, or from among multiple potential living donors, the transplant clinician must weigh multiple dynamic factors to identify the most optimal donor. This review will cover the key considerations when choosing between potential living donors and will propose a decision-making algorithm.

BACKGROUND/UNASSIGNED:The HIV Organ Policy Equity Act legalizes organ procurement from donors with HIV (HIV D+). A prior survey of Organ Procurement Organizations (OPOs) estimated >2000 HIV D+ referrals/year; however, only 30-35 HIV D+/year have had organs procured. Given this gap, we sought to understand HIV D+ referrals and procurements in practice. METHODS/UNASSIGNED:We prospectively collected data on all OPO-reported HIV D+ referrals, including reasons for nonprocurement. We evaluated trends and compared HIV D+ characteristics by procurement status using regression, chi-squared tests, and Wilcoxon rank-sum tests. RESULTS/UNASSIGNED: < 0.001). Nonprocurement was attributed to medical reasons in 63% of cases, of which 36% were AIDS-defining infections and 64% were HIV-unrelated, commonly due to organ failure (36%), high neurologic function (31%), and cancer (14%). Nonprocurement was attributed to nonmedical reasons in 26% of cases, commonly due to no authorization (42%), no waitlist candidates (21%), or no transplant center interest (20%). CONCLUSIONS/UNASSIGNED:In the early years of the HIV Organ Policy Equity Act, actual HIV D+ referrals were much lower than prior estimates; however, the numbers and procurement rates increased over time. Nonprocurement was attributed to both medical and nonmedical issues, and addressing these issues could increase organ availability.

OBJECTIVE:Lung transplants from donors with hepatitis C (HCV D+) have excellent outcomes, but these organs continue to be declined. We evaluated whether (1) being listed to consider and (2) accepting versus declining HCV D+ offers provided a survival benefit to lung transplant candidates. METHODS:Using the Scientific Registry of Transplant Recipients, we identified all adult (≥18 years) lung transplant candidates 2016-2021 and compared waitlist mortality between those willing versus not willing to consider HCV D+ offers using competing risk regression. We identified all candidates offered an HCV D+ lung that was later accepted and followed them from offer decision until death or end-of-study. We estimated adjusted mortality risk of accepting versus declining an HCV D+ lung offer using propensity-weighted Cox regression. RESULTS:From 2016 to 2021, we identified 21,007 lung transplant candidates, 33.8% of whom were willing to consider HCV D+ offers. Candidates willing to consider HCV D+ offers had a 17% lower risk of waitlist mortality (subhazard ratio, 0.83; 95% confidence interval, 0.75-0.91, P < .001). Over the same period, 665 HCV D+ lung offers were accepted after being declined a total of 2562 times. HCV D+ offer acceptance versus decline was associated with a 20% lower risk of mortality (adjusted hazard ratio, 0.80; 95% confidence interval, 0.66-0.96, P = .02). CONCLUSIONS:Considering HCV D+ lung offers was associated with a 17% lower risk of waitlist mortality, whereas accepting versus declining an HCV D+ lung offer was associated with a 20% lower risk of mortality. Centers and candidates should consider accepting suitable HCV D+ lung offers to optimize outcomes.

BACKGROUND:Though older adults with chronic kidney disease (CKD) have a greater mortality risk than those without CKD, traditional risk factors poorly predict mortality in this population. Therefore, we tested our hypothesis that two common geriatric risk factors, frailty and cognitive impairment, and their co-occurrence, might improve mortality risk prediction in CKD. METHODS:Among participants aged ≥ 60 years from National Health and Nutrition Examination Survey (2011-2014), we quantified associations between frailty (physical frailty phenotype) and global/domain-specific cognitive function (immediate-recall [CERAD-WL], delayed-recall [CERAD-DL], verbal fluency [AF], executive function/processing speed [DSST], and global [standardized-average of 4 domain-specific tests]) using linear regression, and tested whether associations differed by CKD using a Wald test. We then tested whether frailty, global cognitive impairment (1.5SD below the mean), or their combination improved prediction of mortality (Cox models, c-statistics) compared to base models (likelihood-ratios) among those with and without CKD. RESULTS: < 0.001) but not cognitive impairment. CONCLUSIONS:Frailty is associated with worse cognitive function regardless of CKD status. While CKD and frailty improved mortality prediction, cognitive impairment did not. Risk prediction tools should incorporate frailty to improve mortality prediction among those with CKD.

BACKGROUND/UNASSIGNED:Among heart transplant candidates, atrial fibrillation (AF) is a common comorbidity; however, little is known about the impact of pre-transplant AF on incidence of post-transplant AF or other transplant outcomes. METHODS/UNASSIGNED:Adult heart transplant recipients transplanted from 07/01/2012 to 07/01/2021 with data available in both the Scientific Registry of Transplant Recipients and Symphony Health pharmacy databases were included. Recipients were categorized by presence of pre-transplant AF using prescription fill data. Perioperative outcomes and survival out to 5 years post-transplant were compared between those with and without pre-transplant AF. RESULTS/UNASSIGNED:Of the 11,789 heart transplant recipients, 2,477 (21.0%) had pre-transplant AF. Pre-transplant AF was associated with an increased likelihood of pre-discharge stroke (aOR 2.13 [95%CI: 1.07-4.26], p=0.03) and dialysis (aOR 1.45 [1.05-2.00], p=0.02), as well as of post-transplant AF at 6 months (aOR 2.42 [1.44-1.48], p=0.001) and 1 year (aOR 2.81 [1.72-4.56], p<0.001). Pre-transplant AF was associated with increased post-transplant mortality at 30 days (aHR 2.39 [1.29-4.44], p=0.006) and 1 year (aHR 1.46 [95% CI: 1.01-2.13], p=0.04), but similar mortality at 5 years (aHR 1.23 [0.96-1.58], p=0.11). CONCLUSION/UNASSIGNED:Heart transplant recipients with pre-transplant AF had worse short-term outcomes and increased risk of developing post-transplant AF but comparable survival at 5 years post-transplant. Our findings emphasize the importance of increased monitoring for perioperative complications and highlight the long-term safety of heart transplantation in this population. WHAT IS NEW?/UNASSIGNED:Patients with atrial fibrillation who undergo heart transplantation have worse short term survival (30-days and 1-year) but similar long term survival (5-years) compared to recipients without pre-transplant atrial fibrillation.Pre-transplant atrial fibrillation increases the risk of clinically significant post-transplant atrial fibrillation and peri-operative stroke.Rate vs rhythm control pharmacotherapy for atrial fibrillation is not associated with differences in survival in heart transplant recipients with pre-transplant atrial fibrillation. WHAT ARE THE CLINICAL IMPLICATIONS?/UNASSIGNED:Atrial fibrillation should not deter heart transplantation in appropriate candidates, though cardiovascular and stroke risk adjustment may be warranted.Use of amiodarone at doses ≤ 200 mg/day is not associated with reduced survival in heart transplant recipients with pre-transplant atrial fibrillation.

Kidney transplant recipients (KTRs) develop decreased antibody titers to SARS-CoV-2 vaccination compared to healthy controls (HCs), but whether KTRs generate antibodies against key epitopes associated with neutralization is unknown. Plasma from 78 KTRs from a clinical trial of third doses of SARS-CoV-2 vaccines and 12 HCs underwent phage display immunoprecipitation and sequencing (PhIP-Seq) to map antibody responses against SARS-CoV-2. KTRs had lower antibody reactivity to SARS-CoV-2 than HCs, but KTRs and HCs recognized similar epitopes associated with neutralization. Thus, epitope gaps in antibody breadth of KTRs are unlikely responsible for decreased efficacy of SARS-CoV-2 vaccines in this immunosuppressed population.

Immune responses to COVID-19 vaccination are attenuated in adult solid organ transplant recipients (SOTRs) and additional vaccine doses are recommended for this population. However, whether COVID-19 mRNA vaccine responses are limited in pediatric SOTRs (pSOTRs) compared to immunocompetent children is unknown. Due to SARS-CoV-2 evolution and mutations that evade neutralizing antibodies, T cells may provide important defense in SOTRs who mount poor humoral responses. Therefore, we assessed anti-SARS-CoV-2 IgG titers, surrogate neutralization, and spike (S)-specific T-cell responses to COVID-19 mRNA vaccines in pSOTRs and their healthy siblings (pHCs) before and after the bivalent vaccine dose. Despite immunosuppression, pSOTRs demonstrated humoral responses to both ancestral strain and Omicron subvariants following the primary ancestral strain monovalent mRNA COVID-19 series and multiple booster doses. These responses were not significantly different from those observed in pHCs and significantly higher six months after vaccination than responses in adult SOTRs two weeks post-vaccination. However, pSOTRs mounted limited S-specific CD8⁺ T-cell responses and qualitatively distinct CD4⁺ T-cell responses, primarily producing IL-2 and TNF with less IFN-γ production compared to pHCs. Bivalent vaccination enhanced humoral responses in some pSOTRs but did not shift the CD4⁺ T-cell responses toward increased IFN-γ production. Our findings indicate that S-specific CD4⁺ T cells in pSOTRs have distinct qualities with unknown protective capacity, yet vaccination produces cross-reactive antibodies not significantly different from responses in pHCs. Given altered T-cell responses, additional vaccine doses in pSOTRs to maintain high titer cross-reactive antibodies may be important in ensuring protection against SARS-CoV-2.

BACKGROUND:Evidence suggests that older patients are less frequently placed on the waiting list for kidney transplantation (KT) than their younger counterparts. The trends and magnitude of this age disparity in access to first KT and repeat KT (re-KT) remain unclear. METHODS:Using the US Renal Data System, we identified 2 496 743 adult transplant-naive dialysis patients and 110 338 adult recipients with graft failure between 1995 and 2018. We characterized the secular trends of age disparities and used Cox proportional hazard models to compare the chances of listing and receiving first KT versus re-KT by age (18-64 y versus ≥65 y). RESULTS:Older transplant-naive dialysis patients were less likely to be listed (adjusted hazard ratio [aHR] = 0.18; 95% confidence interval [CI], 0.17-0.18) and receive first KT (aHR = 0.88; 95% CI, 0.87-0.89) compared with their younger counterparts. Additionally, older patients with graft failure had a lower chance of being listed (aHR = 0.40; 95% CI, 0.38-0.41) and receiving re-KT (aHR = 0.76; 95% CI, 0.72-0.81). The magnitude of the age disparity in being listed for first KT was greater than that for re-KT ( Pinteraction  < 0.001), and there were no differences in the age disparities in receiving first KT or re-KT ( Pinteraction  = 0.13). Between 1995 and 2018, the age disparity in listing for first KT reduced significantly ( P  < 0.001), but the age disparities in re-KT remained the same ( P  = 0.16). CONCLUSIONS:Age disparities exist in access to both first KT and re-KT; however, some of this disparity is attenuated among older adults with graft failure. As the proportion of older patients with graft failure rises, a better understanding of factors that preclude their candidacy and identification of appropriate older patients are needed.