Faculty Bibliography

RATIONALE AND OBJECTIVE/OBJECTIVE:Compared to recipients of ABO-compatible (ABOc) living donor kidney transplants (LDKT), recipients of ABO-incompatible (ABOi) LDKT have a higher risk of graft loss, particularly in the first few weeks after transplantation. However, the decision to proceed with ABOi LDKT should be based on a comparison of the alternative: waiting for future ABOc LDKT (e.g, through kidney paired exchange) or for a deceased donor kidney transplant (DDKT). We sought to evaluate the patient survival difference between ABOi LDKT and waiting for an ABOc LDKT or an ABOc DDKT. STUDY DESIGN/METHODS:Retrospective cohort study of adults in the Scientific Registry of Transplant Recipients (SRTR) SETTING AND PARTICIPANTS: 808 ABOi LDKT recipients and 2423 matched controls from among 245,158 adult, first-time kidney-only waitlist registrants who did not receive an ABOi LDKT and who remained on the waitlist or received either an ABOc LDKT or an ABOc DDKT, 2002-2017 EXPOSURE: Receipt of ABOi LDKT OUTCOME: Death ANALYTICAL APPROACH: We compared mortality among ABOi LDKT recipients versus a weighted matched comparison population using Cox proportional hazards regression as well as Cox models that accommodated for changing hazards ratios over time. RESULTS:Compared to matched controls, ABOi LDKT was associated with lower survival risk in the first 30 days post-transplant (99.0% vs 99.6%, respectively), but higher survival risk beyond 180 days post-transplant. Patients who received ABOi LDKT had higher survival at 5 and 10 years (90.0% and 75.4% respectively) than similar patients who remained on the waitlist or received ABOc LDKT or ABOc DDKT (81.9% and 68.4% respectively). LIMITATIONS/CONCLUSIONS:No measurement of ABO antibody titers in recipients; eligibility of participants for kidney paired donation is unknown. CONCLUSIONS:Transplant candidates who receive an ABOi LDKT and survive more than 180 days post-transplant experience a long-term survival benefit compared to remaining on the waitlist to potentially receive an ABO compatible kidney transplant.

An increasing number of studies claim machine learning (ML) predicts transplant outcomes more accurately. However, these claims were possibly confounded by other factors, namely, supplying new variables to ML models. To better understand the prospects of ML in transplantation, we compared ML to conventional regression in a "common" analytic task: predicting kidney transplant outcomes using national registry data. We studied 133 431 adult deceased-donor kidney transplant recipients between 2005 and 2017. Transplant centers were randomly divided into 70% training set (190 centers/97 787 recipients) and 30% validation set (82 centers/35 644 recipients). Using the training set, we performed regression and ML procedures [gradient boosting (GB) and random forests (RF)] to predict delayed graft function, one-year acute rejection, death-censored graft failure C, all-cause graft failure, and death. Their performances were compared on the validation set using -statistics. In predicting rejection, regression (C = _0.601 0.611_0.621 ) actually outperformed GB (C = _0.581 0.591_0.601 ) and RF (C = _0.569 0.579_0.589 ). For all other outcomes, the C-statistics were nearly identical across methods (delayed graft function, 0.717-0.723; death-censored graft failure, 0.637-0.642; all-cause graft failure, 0.633-0.635; and death, 0.705-0.708). Given its shortcomings in model interpretability and hypothesis testing, ML is advantageous only when it clearly outperforms conventional regression; in the case of transplant outcomes prediction, ML seems more hype than helpful.

Many deceased-donor and living-donor kidney transplants (KTs) rely on commercial airlines for transport. However, the coronavirus-19 pandemic has drastically impacted the commercial airline industry. To understand potential pandemic-related disruptions in the transportation network of kidneys across the United States, we used national flight data to compare scheduled flights during the pandemic vs 1-year earlier, focusing on Organ Procurement Organization (OPO) pairs between which kidneys historically most likely traveled by direct flight (High Volume by direct Air transport OPO Pairs, HVA-OPs). Across the United States, there were 39% fewer flights in April 2020 vs April 2019. Specific to the kidney transportation network, there were 65.1% fewer flights between HVA-OPs, with considerable OPO-level variation (interquartile range [IQR] 54.7%-75.3%; range 0%-100%). This translated to a drop in median number of flights between HVA-OPs from 112 flights/wk in April 2019 to 34 in April 2020 (P < .001), and a rise in wait time between scheduled flights from 1.5 hours in April 2019 (IQR 0.76-3.3) to 4.9 hours in April 2020 (IQR 2.6-11.2; P < .001). Fewer flights and longer wait times can impact logistics as well as cold ischemia time; our findings motivate an exploration of creative approaches to KT transport as the impact of this pandemic on the airline industry evolves.

As the field of Vascular Composite Allotransplantation (VCA) grows, demand for VCA donations will increase. The public should be made aware of this treatment option to support patients' informed decision-making and authorization for deceased donation. We assessed the availability and quality of existing VCA public education materials from organ procurement organizations (OPOs), transplant centers, the Organ Procurement and Transplant Network, Veterans Affairs, and the Department of Defense. A content analysis was performed to identify topics covered and important gaps. In total, 1314 public education materials were analyzed, including OPO Facebook posts (61.6%), OPO Twitter posts (29.9%), websites (6.4%), and written documents (eg, fact sheets, research reports) (2.1%). Upper extremity (34.7%) and face (34.5%) transplants were more commonly covered than reproductive (6.4%) or other VCA types (2.8%). Most materials (76.6%) referenced a specific VCA story. However, few materials described which patient population could benefit from VCA (eg, Veterans, amputees, burn victims, 16.4%), the authorization requirements for VCA donation (6.6%), or the appearance of transplanted VCA organs (1.2%). Current VCA public education materials do not adequately educate the public. More comprehensive education materials are needed to prepare the public to authorize VCA donation, become potential donors, or learn about transplant options.

Kidney transplant recipients who develop symptoms consistent with coronavirus disease 2019 (COVID-19) are bringing unique challenges to health care professionals. Telemedicine has surged dramatically since the pandemic in effort to maintain patient care and reduce the risk of COVID-19 exposure to patients, health care workers, and the public. Herein we present reports of 3 kidney transplant recipients with COVID-19 who were managed using telemedicine via synchronous video visits integrated with an electronic medical record system, from home to inpatient settings. We demonstrate how telemedicine helped assess, diagnose, triage, and treat patients with COVID-19 while avoiding a visit to an emergency department or outpatient clinic. While there is limited information about the duration of viral shedding for immunosuppressed patients, our findings underscore the importance of using telemedicine in the follow-up care for kidney transplant recipients with COVID-19 who have recovered from symptoms but might have persistently positive nucleic acid tests. Our experience emphasizes the opportunities of telemedicine in the management of kidney transplant recipients with COVID-19 and in the maintenance of uninterrupted follow-up care for such immunosuppressed patients with prolonged viral shedding. Telemedicine may help increase access to care for kidney transplant recipients during and beyond the pandemic as it offers a prompt, safe, and convenient platform in the delivery of care for these patients. Yet, to advance the practice of telemedicine in the field of kidney transplantation, barriers to increasing the widespread implementation of telemedicine should be removed, and research studies are needed to assess the effectiveness of telemedicine in the care of kidney transplant recipients.

Clinical decision-making in kidney transplant (KT) during the coronavirus disease 2019 (COVID-19) pandemic is understandably a conundrum: both candidates and recipients may face increased acquisition risks and case fatality rates (CFRs). Given our poor understanding of these risks, many centers have paused or reduced KT activity, yet data to inform such decisions are lacking. To quantify the benefit/harm of KT in this context, we conducted a simulation study of immediate-KT vs delay-until-after-pandemic for different patient phenotypes under a variety of potential COVID-19 scenarios. A calculator was implemented (http://www.transplantmodels.com/covid_sim), and machine learning approaches were used to evaluate the important aspects of our modeling. Characteristics of the pandemic (acquisition risk, CFR) and length of delay (length of pandemic, waitlist priority when modeling deceased donor KT) had greatest influence on benefit/harm. In most scenarios of COVID-19 dynamics and patient characteristics, immediate KT provided survival benefit; KT only began showing evidence of harm in scenarios where CFRs were substantially higher for KT recipients (eg, ≥50% fatality) than for waitlist registrants. Our simulations suggest that KT could be beneficial in many centers if local resources allow, and our calculator can help identify patients who would benefit most. Furthermore, as the pandemic evolves, our calculator can update these predictions.

Optimization of maintenance immunosuppression (mIS) regimens in the transplant recipient requires a balance between sufficient potency to prevent rejection and avoidance of excessive immunosuppression to prevent toxicities and complications. The optimal regimen after simultaneous liver-kidney (SLK) transplantation remains unclear, but small single-center reports have shown success with steroid-sparing regimens. We studied 4184 adult SLK recipients using the Scientific Registry of Transplant Recipients, from March 1, 2002, to February 28, 2017, on tacrolimus-based regimens at 1 year post-transplant. We determined the association between mIS regimen and mortality and graft failure using Cox proportional hazard models. The use of steroid-sparing regimens increased post-transplant, from 16.1% at discharge to 88.0% at 5 years. Using multi-level logistic regression modeling, we found center-level variation to be the major contributor to choice of mIS regimen (ICC 44.5%; 95% CI: 36.2%-53.0%). In multivariate analysis, use of a steroid-sparing regimen at 1 year was associated with a 21% decreased risk of mortality compared to steroid-containing regimens (aHR 0.79, P = .01) and 20% decreased risk of liver graft failure (aHR 0.80, P = .01), without differences in kidney graft loss risk (aHR 0.92, P = .6). Among SLK recipients, the use of a steroid-sparing regimen appears to be safe and effective without adverse effects on patient or graft survival.

BACKGROUND:The growth of the aging population coupled with the increasing incidence of thyroid cancer warrants a better understanding of thyroid cancer in older adults. We aimed to investigate the variation of treatment patterns and determine if the extent of surgery is associated with disease-specific mortality in older adults with differentiated thyroid cancer (DTC). METHODS:We performed a population-based study using the Surveillance, Epidemiology, and End Results 18 program to examine patients diagnosed with DTC between 2004 and 2015. Patients were stratified by age: younger adults (aged 18-54 y), middle adults (aged 55-64 y), older adults (aged 65-79 y), and super elderly (aged ≥80 y). Disease-specific mortality was estimated using Kaplan-Meier curves and compared using the log-rank test. Multivariable Cox regression was used to assess associations between clinicopathologic characteristics and treatment patterns on disease-specific mortality. RESULTS:Of 117,098 patients with DTC, 72,368 were younger adults, 23,726 middle adults, 18,119 older adults, and 2885 were super elderly. In patients with DTC, compared with younger adults, fewer middle, older, and super elderly adults underwent any surgery (99.0%, 98.4%, 97.4%, and 89.1%, respectively; P < 0.001) or received radioactive iodine (RAI; 48.7%, 42.5%, 39.7%, and 30.7%, respectively; P < 0.001). Furthermore, middle, older, and super elderly adults had higher risk of mortality from DTC (hazard ratio [HR]: 4.0, 95% confidence interval [CI]: 3.2-4.8, P < 0.001; HR: 7.6, 95% CI: 6.3-9.1, P < 0.001; and HR: 17.2, 95% CI: 13.8-21.3, P < 0.001, respectively). On multivariable Cox regression while adjusting for clinicopathologic confounders, management was a significant prognostic factor (no surgery HR: 3.8, 95% CI: 3.1-4.6, P < 0.001; and RAI HR: 0.7, 95% CI: 0.6-0.8, P < 0.001). CONCLUSIONS:In patients with DTC, fewer older adults (≥65 y) underwent surgery or treatment with RAI, and this was associated with a worse disease-specific survival. Surgical decision-making in the older population is complex, and future prospective studies are needed to assess this age-related treatment variation.

Organs from uncontrolled DCD donors (uDCDs) have expanded donation in Europe since the 1980s, but are seldom used in the United States. Cited barriers include lack of knowledge about the potential donor pool, lack of robust outcomes data, lack of standard donor eligibility criteria and preservation methods, and logistical and ethical challenges. To determine whether it would be appropriate to invest in addressing these barriers and building this practice, we sought to enumerate the potential pool of uDCD donors. Using data from the Nationwide Emergency Department Sample, the largest all-payer emergency department (ED) database, between 2013 and 2016, we identified patients who had refractory cardiac arrest in the ED. We excluded patients with contraindications to both deceased donation (including infection, malignancy, cardiopulmonary disease) and uDCD (including hemorrhage, major polytrauma, burns, and poisoning). We identified 9828 (range: 9454-10 202) potential uDCDs/y; average age was 32 years, and all were free of major comorbidity. Of these, 91.1% had traumatic deaths, with major causes including nonhead blunt injuries (43.2%) and head injuries (40.1%). In the current era, uDCD donors represent a significant potential source of unused organs. Efforts to address barriers to uDCD in the United States should be encouraged.

BACKGROUND:Optimizing antithymocyte globulin (ATG) dosage is critical, particularly for high-risk kidney transplant (KT) recipients without cytomegalovirus (CMV) prophylaxis. METHODS:We studied 630 KT recipients with expanded criteria donors or panel reactive antibody ≥50% at Hospital do Rim, Brazil (January 1, 2013 to May 21, 2015) to determine whether a single ATG dose was safe and effective in patients without CMV prophylaxis. Patients received ≥4 doses (1-1.5 mg/kg/per dose) until June 17, 2014, when the induction protocol changed to a single ATG dose (3 mg/kg). We used Cox regression to compare the risk of CMV infection and acute rejection (AR) among KT recipients by ATG dose. RESULTS:Adjusting for clinical and transplant factors, a single ATG dose was associated with a lower risk of CMV infection (adjusted hazard ratio [aHR]: 0.63; 95% confidence interval [CI], 0.42-0.93; P = 0.02) and a similar risk of AR (aHR: 1.16; 95% CI, 0.47-2.83; P = 0.8), compared to multiple doses. We found no differences in death-censored graft loss (5.0% versus 4.8%, aHR: 1.06; 95% CI, 0.51-2.23; P = 0.9) or mortality (4.7% versus 3.4%; aHR: 1.42; 95% CI, 0.62-3.24; P = 0.4) at 1-year post-KT by ATG dose. CONCLUSIONS:In our study of high-risk KT recipients without CMV prophylaxis, a single ATG dose decreased the risk of CMV infection without increasing the risk of AR or compromising graft or patient survival.