The Effect of the Opioid Epidemic on Donation After Circulatory Death Transplantation Outcomes

Semiparametric g-computation for survival outcomes with time-fixed exposures: An illustration

PURPOSE

Generalized (g-) computation is a useful tool for causal inference in epidemiology. However, in settings when the outcome is a survival time subject to right censoring, the standard pooled logistic regression approach to g-computation requires arbitrary discretization of time, parametric modeling of the baseline hazard function, and the need to expand one's dataset. We illustrate a semiparametric Breslow estimator for g-computation with time-fixed treatments and survival outcomes that is not subject to these limitations.

METHODS

We compare performance of the Breslow g-computation estimator to the pooled logistic g-computation estimator in simulations and illustrate both approaches to estimate the effect of a 3-drug vs 2-drug antiretroviral therapy regimen among people with HIV.

RESULTS

In simulations, both approaches performed well at the end of follow-up. The pooled logistic approach was biased at times between the endpoints of the discrete time intervals used, while the Breslow approach was not. In the example, both approaches estimated a 1-year risk difference of about 6 % in favor of the 3-drug regimen, but the shape of the survival curves differed.

CONCLUSIONS

The Breslow g-computation estimator of counterfactual risk functions does not rely on strong parametric assumptions about the time-to-event distribution or onerous dataset expansions.

Ethical and Equity Guidance for Transplant Programs Considering Thoracoabdominal Normothermic Regional Perfusion (TA-NRP) for Procurement of Hearts

Donation after circulatory determination of death (DCDD) is an accepted practice in the United States, but heart procurement under these circumstances has been debated. Although the practice is experiencing a resurgence due to the recently completed trials using ex vivo perfusion systems, interest in thoracoabdominal normothermic regional perfusion (TA-NRP), wherein the organs are reanimated in situ prior to procurement, has raised many ethical questions. We outline practical, ethical, and equity considerations to ensure transplant programs make well-informed decisions about TA-NRP. We present a multidisciplinary analysis of the relevant ethical issues arising from DCDD-NRP heart procurement, including application of the Dead Donor Rule and the Uniform Definition of Death Act, and provide recommendations to facilitate ethical analysis and input from all interested parties. We also recommend informed consent, as distinct from typical "authorization," for cadaveric organ donation using TA-NRP.

Effect of the opioid crisis on the liver transplantation donor pool: A national analysis

BACKGROUND

Over the last decade there has been a surge in overdose deaths due to the opioid crisis. We sought to characterize the temporal change in overdose donor (OD) use in liver transplantation (LT), as well as associated post-LT outcomes, relative to the COVID-19 era.

METHODS

LT candidates and donors listed between January 2016 and September 2022 were identified from the Scientific Registry of Transplant Recipients database. Trends in LT donors and changes related to OD were assessed pre- versus post-COVID-19 (February 2020).

RESULTS

Between 2016 and 2022, most counties in the United States experienced an increase in overdose-related deaths (n = 1284, 92.3%) with many counties (n = 458, 32.9%) having more than a doubling in drug overdose deaths. Concurrently, there was an 11.2% increase in overall donors, including a 41.7% increase in the number of donors who died from drug overdose. In pre-COVID-19 overdose was the 4th top mechanism of donor death, while in the post-COVID-19 era, overdose was the 2nd most common cause of donor death. OD was younger (OD: 35 yrs, IQR 29-43 vs. non-OD: 43 yrs, IQR 31-56), had lower body mass index (≥35 kg/cm2, OD: 31.2% vs. non-OD: 33.5%), and was more likely to be HCV+ (OD: 28.9% vs. non-OD: 5.4%) with lower total bilirubin (≥1.1 mg/dL, OD: 12.9% vs. non-OD: 20.1%) (all p < .001). Receipt of an OD was not associated with worse graft survival (HR .94, 95% CI .88-1.01, p = .09).

CONCLUSIONS

Opioid deaths markedly increased following the COVID-19 pandemic, substantially altering the LT donor pool in the United States.

Implications of drug intoxication on donor utilization and outcomes in liver transplantation

INTRODUCTION

This study evaluates the implications of drug intoxication (DI) on donor utilization and outcomes in liver transplantation (LT).

METHODS

The UNOS STAR database was evaluated for all potential donors and adult, first-time, whole LT between 2005 and 2019. Logistic regression analyses evaluated liver utilization; proportional hazards modeling assessed risk of 1-year graft loss.

RESULTS

A total of 132 783 potential donors (10 205, 7.7% from DI), and 90 612 adult LT were identified (7490, 8.3% from DI). DI donors had median age 32 years (IQR 26-40 years, p < .001), were 42.6% female (n = 4346), and 15.5% were DCD donors (n = 1583). Utilization of DI donors changed over time, such that by 2015-2019 they were the most likely donor cause of death (COD) to be utilized. Among LT recipients, there were insignificant differences (<2% variance) in age, gender, ethnicity, and etiology of liver disease according to donor COD. Recipients with MELD scores >30 more frequently received grafts from donors with trauma (23.8%) and DI (21.8%) versus cardiovascular (20.0%) and CVA/stroke (19.9%, p < .001). Among DBD donors, DI-COD was associated with superior 1-year graft survival compared to donors from trauma (HR 1.172, 95% CI 1.057-1.300) and CVA/stroke (HR 1.404, 95% CI 1.264-1.561, p < .001). Donor COD was not significantly associated with 1-year graft loss among DCD donors.

CONCLUSIONS

There is an increased likelihood of donor utilization when COD is drug overdose and an increased likelihood of 1-year graft survival compared to donors from trauma, CVA/stroke, and other COD.

The changing epidemiology of adult liver transplantation in the United States in 2013-2022: The dominance of metabolic dysfunction-associated steatotic liver disease and alcohol-associated liver disease

BACKGROUND

The high prevalence of obesity in the United States drives the burden of NASH, recently renamed as metabolic dysfunction-associated steatohepatitis (MASH). We assessed the most recent trends in liver transplantation in the United States.

METHODS

The Scientific Registry of Transplant Recipients (SRTR 2013-2022) was used to select adult (18 years or above) candidates who underwent liver transplant.

RESULTS

There were 116,292 candidates who underwent liver transplant with known etiology of chronic liver disease. In candidates without HCC, the most common etiology was alcohol-associated liver disease (ALD), increasing from 23% (2013) to 48% (2022), followed by NASH/MASH, which increased from 19% to 27%; the rates of viral hepatitis decreased (chronic hepatitis C: 28%-4%; chronic hepatitis B: 1.8%-1.1%) (all trend p<0.01). The proportion of HCC decreased from 25% (2013-2016) to 17% (2021-2022). Among HCC cohort, the proportion of chronic hepatitis C decreased from 60% (2013) to 27% (2022), NASH/MASH increased from 10% to 31%, alcohol-associated liver disease increased from 9% to 24% (trend p<0.0001), and chronic hepatitis B remained stable between 5% and 7% (trend p=0.62). The rapid increase in the proportion of NASH/MASH in HCC continued during the most recent study years [20% (2018), 28% (2020), 31% (2022)]; the trend remained significant after adjustment for age, sex, ethnicity, obesity, and type 2 diabetes.

CONCLUSIONS

Liver transplant etiologies in the United States have changed over the last decade. Alcohol-associated liver disease and NASH/MASH remain the 2 most common indications for transplantation among those without HCC, and NASH/MASH is the most common in patients with HCC.

Transplant Candidate Outcomes After Declining a DCD Liver in the United States

BACKGROUND

In the context of the organ shortage, donation after circulatory death (DCD) provides an opportunity to expand the donor pool. Although deceased-donor liver transplantation from DCD donors has expanded, DCD livers continue to be discarded at elevated rates; the use of DCD livers from older donors, or donors with comorbidities, is controversial.

METHODS

Using US registry data from 2009 to 2020, we identified 1564 candidates on whose behalf a DCD liver offer was accepted ("acceptors") and 16 981 candidates on whose behalf the same DCD offers were declined ("decliners"). We characterized outcomes of decliners using a competing risk framework and estimated the survival benefit (adjusted hazard ratio [95% confidence interval]) of accepting DCD livers using Cox regression.

RESULTS

Within 10 y of DCD offer decline, 50.9% of candidates died or were removed from the waitlist before transplantation with any type of allograft. DCD acceptors had lower mortality compared with decliners at 10 y postoffer (35.4% versus 48.9%, P < 0.001). After adjustment for candidate covariates, DCD offer acceptance was associated with a 46% reduction in mortality (0.54 [0.49-0.61]). Acceptors of older (age ≥50), obese (body mass index ≥30), hypertensive, nonlocal, diabetic, and increased risk DCD livers had 44% (0.56 [0.42-0.73]), 40% (0.60 [0.49-0.74]), 48% (0.52 [0.41-0.66]), 46% (0.54 [0.45-0.65]), 32% (0.68 [0.43-1.05]), and 45% (0.55 [0.42-0.72]) lower mortality risk compared with DCD decliners, respectively.

CONCLUSIONS

DCD offer acceptance is associated with considerable long-term survival benefits for liver transplant candidates, even with older DCD donors or donors with comorbidities. Increased recovery and utilization of DCD livers should be encouraged.

Observational Study Examining Kidney Transplantation Outcomes Following Donation From Individuals That Died of Drug Toxicity in British Columbia, Canada

Background:

The illicit drug toxicity (overdose) crisis has worsened across Canada, between 2016 and 2021 more than 28 000 individuals have died of drug toxicity. Organ donation from persons who experience drug toxicity death has increased in recent years.

Objective:

This study examines whether graft loss after kidney transplantation differed by donor cause of death.

Design:

Retrospective cohort.

Setting:

Provincial transplant program of British Columbia, Canada.

Patients:

Transplant recipients who received kidney transplantation from deceased donors aged 12 to 70 years between 2013 and 2019 (N = 1012).

Measurements:

Transplant recipient all cause graft loss (graft loss due to any cause including death) was compared by donor cause of death from drug toxicity or other.

Methods:

Five-year Kaplan-Meier estimates of all-cause graft survival, and 3-year complete as well as stratified inverse probability of treatment weighted Cox proportional hazards models were conducted.

Results:

Drug toxicity death donors donated to 25% (252/1012) of kidney transplantations. Drug toxicity death donors were more likely to be young, white, males, with fewer comorbidities such as diabetes or hypertension but were more likely to have a terminal serum creatinine ≥1.5 mg/dL or be hepatitis C virus (HCV) positive. Unadjusted 5-year estimate of all-cause graft survival was 97% for recipients of drug toxicity donor kidneys and 83% for recipients of non-drug toxicity donor kidneys ( P < .001). Recipients of drug toxicity death donor kidneys had decreased risk of all cause graft loss compared to recipients of non-drug toxicity death donor kidneys (hazard ratio [HR]: 0.30, 95% confidence interval [CI]: 0.12-0.77, P = .012). This is primarily due to the reduced risk of all-cause graft loss for recipients of younger (≤35 years) drug toxicity death donor kidneys (HR: 0.05, 95% CI: 0.00-0.55, P = .015).

Limitations:

Potential selection bias, potential unmeasured confounding.

Conclusions:

Donation after drug toxicity death is safe and should be considered more broadly to increase deceased donor kidney donation.

The Surge in Deceased Liver Donors Due to the Opioid Epidemic: Is It Time to Split the Difference?

BACKGROUND

This study aimed to compare trends in use of drug overdose (DO) donors in adult versus pediatric liver transplants and the utilization of split liver transplantation in this donor population.

METHODS

The United Network for Organ Sharing database was reviewed for deceased donor liver transplants from March 2002 to December 2017. Recipients were categorized by donor mechanism of death. Donor splitting criteria was defined as age <40 y, single vasopressor or less, transaminases no >3 times the normal limit, and body mass index ≤ 28 kg/m2.

RESULTS

Adult liver transplants from DO donors increased from 2% in 2002 to 15% in 2017, while pediatric liver transplants from DO donors only increased from <1% to 3% in the same time. While 28% of DO donors met splitting criteria, only 3% of those meeting splitting criteria were used as a split graft. Both pediatric and adult recipients of DO donor livers achieved excellent patient and graft survival.

CONCLUSIONS

DO donors are underutilized in pediatric liver transplantation. Increased splitting of DO donor livers could significantly decrease, if not eliminate, the pediatric liver waiting list.

Opioids and Kidney Transplantation

The United States has faced an unprecedented opioid crisis in recent years, which has led to an increase in opioid overdose-related deaths and, consequently, an increase in the number of potential deceased donors available for transplantation. This new pool of potential organ donors is composed of younger donors with higher infectious disease transmission risk. The use of organs from these donors requires appropriate patient education, informed consent, and post-transplant monitoring practices. Prescription opioid use is also an important component of the evaluation of transplant and living donor candidates because it may impact outcomes and eligibility for the procedures. In kidney transplant recipients, prescription opioid use predicts a higher risk of mortality, graft loss, and post-transplant complications. These effects seem to be proportional to the levels of opioid use, and to parallel patterns in other transplant populations such as liver, heart and lung recipients. Among living kidney donors, predonation prescription opioid use is associated with an increased risk of re-admission after nephrectomy. Overall, the opioid epidemic creates educational needs for patients awaiting deceased donor transplant, and also impacts the evaluation and care of transplant candidates. Among transplant candidates and recipients, the identification of patients with chronic opioid use should prompt multidisciplinary evaluation and management strategies to minimize risks.

Attitudes Toward Organ Donation for Persons Who Have a Substance Use Disorder Relative to Other Health Conditions

Background: Increases in opioid-related overdose and death have led to increases in the number of organs available for donation and transplant, however persons who have a substance use disorder (SUD) may be disadvantaged relative to other health conditions with regard to receiving an organ for transplant. Objective: This study aimed to evaluate perceptions regarding acceptability and priority for organ donation vs. a control condition (resuscitation) for hypothetical persons with nine target health conditions including a substance use disorder, among persons recruited as part of an online survey. Methods: Respondents (N = 285; male = 172, female = 113) recruited from Amazon Mechanical Turk rated acceptability and priority that hypothetical persons representing nine target health conditions expected to influence transplant success (including a SUD) receive an organ transplant and resuscitation via a survey hosted by Qualtrics. Primary outcomes of stigma ratings and priority ranking of persons as a function of the hypothetical target health condition were analyzed using Repeated Measures Analyses of Variance and Bonferroni-corrected t-tests. Demographic information was presented descriptively for all respondents. Results: Ratings for acceptability and priority for persons who had a SUD were generally lower than ratings for other conditions for both organ for transplant and resuscitation, though respondents reported less stigma toward resuscitation, F ₍₈₎ = 22.35, p <0.001 overall. Respondents were least supportive of persons who smoked cigarettes receiving an organ, p's < 0.001. Priority rankings favored persons who were young or had a history of heart disease. Multivariable models determined that target health condition, F ₍₈₎ = 33.64, p < 0.001, was a better and more consistent predictor of response than demographic variables that were examined. Conclusions: Data suggest that general perception of acceptability and priority ranking for receipt of life-saving interventions was lower for persons who have a SUD relative to other clinically-relevant health conditions. Research to examine this effect among persons working in the donation system are warranted and efforts to reduce stigma toward persons who have a SUD should be continued.

Liver and Kidney Recipient Selection of Hepatitis C Virus Viremic Donors: Meeting Consensus Report From the 2019 Controversies in Transplantation

The development of multiple highly effective and safe direct-acting antivirals to treat hepatitis C virus (HCV) has resulted in greater ease and confidence in managing HCV infection in transplant recipients that in turn has impacted the solid organ transplant community as well. In the United States, the opioid epidemic has increased the number of overdose deaths with a concomitant increase in younger HCV viremic donors after brain death being identified. At the same time, a decrease in HCV viremic transplant candidates has led to a growing interest in exploring the use of HCV viremic liver and kidney donor allografts in HCV-negative recipients. To date, experience with the use of HCV viremic liver and kidney allografts in HCV-negative recipients is limited to a few small prospective research trials, case series, and case reports. There are also limited data on recipient and donor selection for HCV viremic liver and kidney allografts. In response to this rapidly changing landscape in the United States, experts in the field of viral hepatitis and liver and kidney transplantation convened a meeting to review current data on liver and kidney recipient selection and developed consensus opinions related specifically to recipient and donor selection of HCV viremic liver and kidney allografts.

Wide Variation in the Percentage of Donation After Circulatory Death Donors Across Donor Service Areas: A Potential Target for Improvement

BACKGROUND

Substantial differences exist in the clinical characteristics of donors across the 58 donor service areas (DSAs). Organ procurement organization (OPO) performance metrics incorporate organs donated after circulatory determination of death (DCDD) donors but do not measure potential DCDD donors.

METHODS

Using 2011-2016 United Network for Organ Sharing data, we examined the variability in DCDD donors/all deceased donors (%DCDD) across DSAs. We supplemented United Network for Organ Sharing data with CDC death records and OPO statistics to characterize underlying process and system factors that may correlate with donors and utilization.

RESULTS

Among 52 184 deceased donors, the %DCDD varied widely across DSAs, with a median of 15.1% (interquartile range [9.3%, 20.9%]; range 0.0%-32.0%). The %DCDD had a modest positive correlation with 4 DSA factors: median match model for end-stage liver disease, proportion of white deaths out of total deaths, kidney center competition, and %DCDD livers by a local transplant center (all Spearman coefficients 0.289-0.464), and negative correlation with 1 factor: mean kidney waiting time (Spearman coefficient -0.388). Adjusting for correlated variables in linear regression explained 46.3% of the variability in %DCDD.

CONCLUSIONS

Donor pool demographics, waitlist metrics, center competition, and DCDD utilization explain only a portion of the variability of DCDD donors. This requires further studies and policy changes to encourage consideration of all possible organ donors.

Clinical Implications of Donor Warm and Cold Ischemia Time in Donor After Circulatory Death Liver Transplantation

The use of donation after circulatory death (DCD) liver allografts has been constrained by limitations in the duration of donor warm ischemia time (DWIT), donor agonal time (DAT), and cold ischemia time (CIT). The purpose of this study is to assess the impact of longer DWIT, DAT, and CIT on graft survival and other outcomes in DCD liver transplants. The Scientific Registry of Transplant Recipients was queried for adult liver transplants from DCD donors between 2009 and 2015. Donor, recipient, and center variables were included in the analysis. During the study period, 2107 patients underwent liver transplant with DCD allografts. In most patients, DWIT and DAT were <30 minutes. DWIT was <30 minutes in 1804 donors, between 30 and 40 minutes in 248, and >40 minutes in 37. There was no difference in graft survival, duration of posttransplant hospital length of stay, and readmission rate between DCD liver transplants from donors with DWIT <30 minutes and DWIT between 30 and 40 minutes. Similar outcomes were noted for DAT. In the multivariate analysis, DAT and DWIT were not associated with graft loss. The predictors associated with graft loss were donor age, donor sharing, CIT, recipient admission to the intensive care unit, recipient ventilator dependence, Model for End-Stage Liver Disease score, and low-volume transplant centers. Any CIT cutoff >4 hours was associated with increased risk for graft loss. Longer CIT was also associated with a longer posttransplant hospital stay, higher rate of primary nonfunction, and hyperbilirubinemia. In conclusion, slightly longer DAT and DWIT (up to 40 minutes) were not associated with graft loss, longer posttransplant hospitalization, or hospital readmissions, whereas longer CIT was associated with worse outcomes after DCD liver transplants.