Contemporary Issues in Lung Transplant Allocation Practices

Evaluating US Multiple Listing Practices in Lung Transplantation: Unveiling Hidden Disparities

BACKGROUND

Multiple listing (ML) is a practice used to increase the potential for transplant but is controversial due to concerns that it disproportionately benefits patients with greater access to health care resources.

RESEARCH QUESTION

Is there disparity in ML practices based on social deprivation in the United States and does ML lead to quicker time to transplant?

STUDY DESIGN AND METHODS

A retrospective cohort study of adult (≥ 18 years of age) lung transplant candidates listed for transplant (2005-2018) was conducted. Exclusion criteria included heart only or heart and lung transplant and patients relisted during the observation period. Data were obtained from the United Network for Organ Sharing Standard Transplant Analysis and Research File. The first exposure of interest was the Social Deprivation Index with a primary outcome of ML status, to assess disparities between ML and single listing (SL) participants. The second exposure of interest was ML status with a primary outcome of time to transplant, to assess whether implementation of ML leads to quicker time to transplant.

RESULTS

A total of 35,890 patients were included in the final analysis, of whom 791 (2.2%) were ML and 35,099 (97.8%) were SL. ML participants had lower median level of social deprivation (5 units, more often female: 60.0% vs 42.3%) and lower median lung allocation score (35.3 vs 37.3). ML patients were more likely to be transplanted than SL patients (OR, 1.42; 95% CI, 1.17-1.73), but there was a significantly quicker time to transplant only for those whom ML was early (within 6 months of initial listing) (subdistribution hazard ratio, 1.17; 95% CI, 1.04-1.32).

INTERPRETATION

ML is an uncommon practice with disparities existing between ML and SL patients based on several factors including social deprivation. ML patients are more likely to be transplanted, but only if they have ML status early in their transplant candidacy. With changing allocation guidelines, it is yet to be seen how ML will change with the implementation of continuous distribution.

Inconsistent values and algorithmic fairness: a review of organ allocation priority systems in the United States

BACKGROUND

The Organ Procurement and Transplant Network (OPTN) Final Rule guides national organ transplantation policies, mandating equitable organ allocation and organ-specific priority stratification systems. Current allocation scores rely on mortality predictions.

METHODS

We examined the alignment between the ethical priorities across organ prioritization systems and the statistical design of the risk models in question. We searched PubMed for literature on organ allocation history, policy, and ethics in the United States.

RESULTS

We identified 127 relevant articles, covering kidney (19), liver (60), lung (24), and heart transplants (23), and transplant accessibility (1). Current risk scores emphasize model performance and overlook ethical concerns in variable selection. The inclusion of race, sex, and geographical limits as categorical variables lacks biological basis; therefore, blurring the line between evidence-based models and discrimination. Comprehensive ethical and equity evaluation of risk scores is lacking, with only limited discussion of the algorithmic fairness of the Model for End-Stage Liver Disease (MELD) and the Kidney Donor Risk Index (KDRI) in some literature. We uncovered the inconsistent ethical standards underlying organ allocation scores in the United States. Specifically, we highlighted the exception points in MELD, the inclusion of race in KDRI, the geographical limit in the Lung Allocation Score, and the inadequacy of risk stratification in the Heart Tier system, creating obstacles for medically underserved populations.

CONCLUSIONS

We encourage efforts to address statistical and ethical concerns in organ allocation models and urge standardization and transparency in policy development to ensure fairness, equitability, and evidence-based risk predictions.

The SHELTER Trial of Transplanting Hepatitis C Virus-Infected Lungs Into Uninfected Recipients

SHELTER is a trial of transplanting lungs from deceased donors with hepatitis C virus (HCV) infection into HCV-negative candidates (sponsor: Merck; NCT03724149). Few trials have reported outcomes using thoracic organs from HCV-RNA+ donors and none have reported quality of life (QOL).

Methods

This study is a single-arm trial of 10 lung transplants at a single center. Patients were included who were between 18 and 67 y of age and waitlisted for lung-only transplant. Patients were excluded who had evidence of liver disease. Primary outcome was HCV cure (sustained virologic response 12 wk after completing antiviral therapy). Recipients longitudinally reported QOL using the validated RAND-36 instrument. We also applied advanced methods to match HCV-RNA+ lung recipients to HCV-negative lung recipients in a 1:3 ratio at the same center.

Results

Between November 2018 and November 2020, 18 patients were consented and opted-in for HCV-RNA+ lung offers in the allocation system. After a median of 37 d (interquartile range [IQR], 6-373) from opt-in, 10 participants received double lung transplants. The median recipient age was 57 y (IQR, 44-67), and 7 recipients (70%) had chronic obstructive pulmonary disease. The median lung allocation score at transplant was 34.3 (IQR, 32.7-86.9). Posttransplant, 5 recipients developed primary graft dysfunction grade 3 on day 2 or 3, although none required extracorporeal membrane oxygenation. Nine patients received elbasvir/grazoprevir, whereas 1 patient received sofosbuvir/velpatasvir. All 10 patients were cured of HCV and survived to 1 y (versus 83% 1-y survival among matched comparators). No serious adverse events were found to be related to HCV or treatment. RAND-36 scores showed substantial improvement in physical QOL and some improvement in mental QOL. We also examined forced expiratory volume in 1 s-the most important lung function parameter after transplantation. We detected no clinically important differences in forced expiratory volume in 1 s between the HCV-RNA+ lung recipients versus matched comparators.

Conclusions

SHELTER adds important evidence regarding the safety of transplanting HCV-RNA+ lungs into uninfected recipients and suggests QOL benefits.

Lung transplant waitlist outcomes among ABO blood groups vary based on disease severity

BACKGROUND

Blood group O candidates have lower lung transplantation rates despite having the most common blood group. We postulated that waitlist outcomes among these candidates and those with other blood types vary with disease severity and lung allocation score (LAS).

METHODS

We performed a retrospective cohort study of 32,772 waitlist candidates using the United Network of Organ Sharing registry from May 2005 to 2020. After identifying an interaction between blood group and LAS, we evaluated the association between blood group and waitlist outcomes within LAS quartiles using unadjusted and adjusted competing risk models.

RESULTS

In the lowest LAS quartile, blood group O had a 20% reduced transplantation rate (SHR: 0.80, 95%CI: 0.75-0.85) and higher waitlist death/removal (1.33, 95%CI: 1.15-1.55) compared with group A. Blood group AB had a 52% higher transplantation rate (SHR: 1.52, 95%CI: 1.34-1.73) in the lowest LAS quartile compared with group A. In the highest LAS quartile, there was no difference in transplantation rates between groups O and A. In contrast, group B had a 19% reduced transplantation rate (SHR, 0.81 95%CI: 0.73-0.89) and AB had a 28% reduced transplantation rate (SHR: 0.72, 95%CI: 0.61-0.86) in the highest LAS quartile. Additionally, groups B and AB had increased risk of waitlist death/removal in the highest LAS quartile compared with A (SHR: 1.27, 95%CI: 1.08-1.48; SHR: 1.31, 95%CI: 1.00-1.72).

CONCLUSIONS

Waitlist outcomes among ABO blood groups vary depending on illness severity, which is represented by LAS. Blood group O has lower transplantation rates at low LAS while groups B and AB have lower transplantation rates at high LAS.

Multiple listing in lung transplant candidates: A cohort study

Lung transplant candidates can be waitlisted at more than one transplant center, a practice known as multiple listing. The factors associated with multiple listing and whether multiple listing modifies waitlist mortality or likelihood of lung transplant is unknown. US lung transplant waitlist candidates were identified as either single or multiple listed using data from the Scientific Registry of Transplant Recipients. Characteristics of single and multiple listed candidates were compared and multivariable logistic regression was used to estimate associations with multiple listing. Multiple listed candidates were matched to single listed candidates using a combination of exact and propensity score matching methods. Cox proportional hazard models were used to estimate the relationship of multiple listing on waitlist mortality and receiving a transplant. Multiple listing occurred in 2.3% of lung transplant waitlist candidates. Younger age, female gender, white race, short stature, high antibody sensitization, college or postcollege education, lower lung allocation score, and a cystic fibrosis diagnosis were independently associated with multiple listing. Multiple listing was associated with an increased likelihood of lung transplant (adjusted hazard ratio [aHR] 2.74, 95% CI 2.37 to 3.16) but was not associated with waitlist mortality (aHR 0.99, 95% CI 0.68 to 1.44).