Gender and racial disparities in lung transplantation in the United States

Racial and Gender Disparities in Transplantation of Hepatitis C+ Hearts and Lungs

BACKGROUND

Transplanting organs from hepatitis C virus (HCV)-infected donors into HCV-negative recipients has led to thousands of more transplants in the United States since 2016. Studies have demonstrated disparities in utilization of kidneys from these donors due to gender and education. It is still unknown, however, if the same disparities are seen in heart and lung transplantation.

METHODS

We used Organ Procurement and Transplantation/United Network for Organ Sharing data on all isolated heart and lung transplants from November 1, 2018, to March 31, 2023, classifying donors based on their HCV nucleic acid test (NAT) result: HCV-NAT- vs HCV-NAT+. We fit separate mixed-effects logistic regression models (outcome: HCV-NAT+ donor) for heart and lung transplants. Primary covariates included (1) race/ethnicity, (2) sex, (3) education level, (4) insurance type, and (5) transplant year.

RESULTS

The study included 26,108 adults (14,189 isolated heart transplant recipients and 11,919 isolated lung transplant recipients). A total of 993 (7.0%) heart transplants involved an HCV-NAT+ donor, compared to 457 (3.8%) lung transplants. In multivariable models among all isolated heart transplant recipients, women were significantly less likely to receive an HCV-NAT+ donor heart (odds ratio [OR]: 0.79, 95% confidence interval [CI]: 0.67-0.92, p = 0.003), as were Asian patients (OR: 0.52, 95% CI: 0.31-0.86, p = 0.01). In multivariable models among all isolated lung transplant recipients, Asians were significantly less likely to receive HCV-NAT+ transplants (OR: 0.31, 95% CI: 0.12-0.77, p = 0.01).

CONCLUSIONS

There are disparities in utilization of heart and lungs from HCV-NAT+ donors, with women and Asian patients being significantly less likely to receive these transplants.

Racial Disparities in Waiting List Outcomes of Patients Listed for Lung Transplantation

BACKGROUND

The Lung Allocation Score, implemented in 2005, prioritized lung transplant candidates by medical urgency rather than waiting list time and was expected to improve racial disparities in transplant allocation. We evaluated whether racial disparities in lung transplant persisted after 2005.

METHODS

We identified all wait-listed adult lung transplant candidates in the United States from 2005 through 2021 using the Scientific Registry of Transplant Recipients. We evaluated the association between race and receipt of a transplant by using a multivariable competing risk regression model adjusted for demographics, socioeconomic status, Lung Allocation Score, clinical measures, and time. We evaluated interactions between race and age, sex, socioeconomic status, and Lung Allocation Score.

RESULTS

We identified 33,158 candidates on the lung transplant waiting list between 2005 and 2021: 27,074 White (82%), 3350 African American (10%), and 2734 Hispanic (8%). White candidates were older, had higher education levels, and had lower Lung Allocation Scores (P < .001). After multivariable adjustment, African American and Hispanic candidates were less likely to receive lung transplants than White candidates (African American: adjusted subhazard ratio, 0.86; 95% CI, 0.82-0.91; Hispanic: adjusted subhazard ratio, 0.82; 95% CI, 0.78-0.87). Lung transplant was significantly less common among Hispanic candidates aged >65 years (P = .003) and non-White candidates from higher-poverty communities (African-American: P = .013; Hispanic: P =.0036).

CONCLUSIONS

Despite implementation of the Lung Allocation Score, racial disparities persisted for wait-listed African American and Hispanic lung transplant candidates and differed by age and poverty status. Targeted interventions are needed to ensure equitable access to this life-saving intervention.

Historic Use of Race-Based Spirometry Values Lowered Transplant Priority for Black Patients

BACKGROUND

The lung allocation score (LAS) is a tool used to prioritize patients for lung transplantation. For patients with interstitial lung diseases (ILDs), spirometry data are used for the LAS calculation. Spirometry values such as a FVC are subjected to race-specific equations that determine expected values. The effect of race-specific equations in LAS score remains unknown.

RESEARCH QUESTION

Did the use of a race-based spirometry equation lead to longer waitlist times for Black patients?

STUDY DESIGN AND METHODS

We performed a retrospective analysis of patients listed for lung transplantation from 2005 through 2020 using publicly available data from the United Network for Organ Sharing. We recalculated LAS scores for Black patients using White-specific equations with the available variables. The primary objective was to evaluate the effect of race-specific equations on LAS scores and time on the transplant waitlist.

RESULTS

A total of 33,845 patients listed for lung transplantation were included in the analysis. White patients were listed at lower LAS scores, a higher proportion of White patients underwent transplantation, and White patients died on the waitlist at lower rates. When recalculating LAS scores using White-specific equations, Black patients with ILD had up to a 1.9-point higher score, which resulted in additional waitlist time.

INTERPRETATION

Race-specific equations led to longer wait times in Black patients listed for lung transplantation. The use of race-based equations widened already known disparities in pulmonary transplantation.

Mitigating Health Disparities in Transplantation Requires Equity, Not Equality

Despite decades of research and evidence-based mitigation strategies, disparities in access to transplantation persist for all organ types and in all stages of the transplant process. Although some strategies have shown promise for alleviating disparities, others have fallen short of the equity goal by providing the same tools and resources to all rather than tailoring the tools and resources to one's circumstances. Innovative solutions that engage all stakeholders are needed to achieve equity regardless of race, sex, age, socioeconomic status, or geography. Mitigation of disparities is paramount to ensure fair and equitable access for those with end-stage disease and to preserve the trust of the public, upon whom we rely for their willingness to donate organs. In this overview, we present a summary of recent literature demonstrating persistent disparities by stage in the transplant process, along with policies and interventions that have been implemented to combat these disparities and hypotheses for why some strategies have been more effective than others. We conclude with future directions that have been proposed by experts in the field and how these suggested strategies may help us finally arrive at equity in transplantation.

Lung transplantation outcomes in patients from socioeconomically distressed communities

BACKGROUND

Previous studies have demonstrated racial and gender disparities in lung allocation, but contemporary data regarding socioeconomic disparities in post-transplant outcomes are lacking. We evaluated the impact of a composite socioeconomic disadvantage index on post-transplant outcomes.

METHODS

The Scientific Registry of Transplant Recipients identified 27,763 adult patients undergoing isolated primary lung transplantation between 2005 and 2020. Zip code-level socioeconomic distress was characterized using the Distressed Communities Index (DCI: 0-no distress, 100-severe distress) based on education level, poverty, unemployment, housing vacancies, median income, and business growth, and patients were stratified into high (DCI ≥60) or low (DCI <60) distressed groups.

RESULTS

Recipients from high-distress communities (n = 8006, 28.8%) were younger (59years [interquartile range {IQR} 50-64] vs 61years [IQR 52-66]), less often white (73 vs 85%), less likely to have a college degree (45 vs 59%), and more likely to have public insurance (57 vs 49%, all p < 0.001) compared to those from low-distress communities. Additionally, high-distress recipients were more likely to have group A diagnoses (32 vs 27%) and undergo bilateral lung transplants (72.4 vs 69.3%, all p < 0.001). Post-transplant survival at 5years was 55.7% (95% confidence interval [CI]: 54.4-56.9) in high-distress recipients and 58.2% (95% CI: 57.4-58.9) in low-distress recipients (p = 0.003). After adjustment, high distress level was independently associated with an increased risk of 5-year mortality (hazard ratio:1.09, 95% CI:1.04-1.15).

CONCLUSIONS

Recipients from distressed communities are at increased mortality risk following lung transplantation. Efforts should be focused on increased resource allocation and further study to better understand factors which may mitigate this disparity.

Race-Specific Interpretation of Spirometry: Impact on the Lung Allocation Score

Rationale: Interpretation of spirometry using race-specific reference equations may contribute to health disparities via underestimation of the degree of lung function impairment in Black patients. The use of race-specific equations may differentially affect patients with severe respiratory disease via the use of percentage predicted forced vital capacity (FVCpp) when included in the lung allocation score (LAS), the primary determinant of priority for lung transplantation. Objectives: To determine the impact of a race-specific versus a race-neutral approach to spirometry interpretation on the LAS among adults listed for lung transplantation in the United States. Methods: We developed a cohort from the United Network for Organ Sharing database including all White and Black adults listed for lung transplantation between January 7, 2009, and February 18, 2015. The LAS at listing was calculated for each patient under race-specific and race-neutral approaches, using the FVCpp generated from the Global Lung Function Initiative equation corresponding to each patient's race (race-specific) or from the Global Lung Function Initiative "other" (race-neutral) equation. Differences in LAS between approaches were compared by race, with positive values indicating a higher LAS under the race-neutral approach. Results: In this cohort of 8,982 patients, 90.3% were White and 9.7% were Black. The mean FVCpp was 4.4% higher versus 3.8% lower among White versus Black patients (P < 0.001) under a race-neutral compared with a race-specific approach. Compared with White patients, Black patients had a higher mean LAS under both a race-specific (41.9 vs. 43.9; P < 0.001) and a race-neutral (41.3 vs. 44.3; P < 0.001) approach. However, the mean difference in LAS under a race-neutral approach was -0.6 versus +0.6 for White versus Black patients (P < 0.001). Differences in LAS under a race-neutral approach were most pronounced for those in group B (pulmonary vascular disease) (-0.71 vs. +0.70; P < 0.001) and group D (restrictive lung disease) (-0.78 vs. +0.68; P < 0.001). Conclusions: A race-specific approach to spirometry interpretation has potential to adversely affect the care of Black patients with advanced respiratory disease. Compared with a race-neutral approach, a race-specific approach resulted in lower LASs for Black patients and higher LASs for White patients, which may have contributed to racially biased allocation of lung transplantation. The future use of race-specific equations must be carefully considered.

Genetic and environmental factors in interstitial lung diseases: current and future perspectives on early diagnosis of high-risk cohorts

Within the wide scope of interstitial lung diseases (ILDs), familial pulmonary fibrosis (FPF) is being increasingly recognized as a specific entity, with earlier onset, faster progression, and suboptimal responses to immunosuppression. FPF is linked to heritable pathogenic variants in telomere-related genes (TRGs), surfactant-related genes (SRGs), telomere shortening (TS), and early cellular senescence. Telomere abnormalities have also been identified in some sporadic cases of fibrotic ILD. Air pollution and other environmental exposures carry additive risk to genetic predisposition in pulmonary fibrosis. We provide a perspective on how these features impact on screening strategies for relatives of FPF patients, interstitial lung abnormalities, ILD multi-disciplinary team (MDT) discussion, and disparities and barriers to genomic testing. We also describe our experience with establishing a familial interstitial pneumonia (FIP) clinic and provide guidance on how to identify patients with telomere dysfunction who would benefit most from genomic testing.

The intersection of race and ethnicity, gender, and primary diagnosis on lung transplantation outcomes

BACKGROUND

Reducing racial disparities in lung transplant outcomes is a current priority of providers, policymakers, and lung transplant centers. It is unknown how the combined effect of race and ethnicity, gender, and diagnosis group is associated with differences in 1-year mortality and 5-year survival.

METHODS

This is a longitudinal cohort study using Standard Transplant Analysis Research files from the United Network for organ sharing. A total of 25,444 patients undergoing first time lung transplantation between 2006 and 2019 in the United States. The primary exposures were lung transplant recipient race and ethnicity, gender, and primary diagnosis group at listing. Multivariable regression models and cox-proportional hazards models were used to determine adjusted 1-year mortality and 5-year survival.

RESULTS

Overall, 25,444 lung transplant patients were included in the cohort including 15,160 (59.6%) men, 21,345 (83.9%) White, 2,318 (9.1%), Black and Hispanic/Latino (7.0%). Overall, men had a significant higher 1-year mortality than women (11.87%; 95% CI 11.07-12.67 vs 12.82%; 95% CI 12.20%-13.44%). Black women had the highest mortality of all race and gender combinations (14.51%; 95% CI 12.15%-16.87%). Black patients with pulmonary vascular disease had the highest 1-year mortality (19.77%; 95% CI 12.46%-27.08%) while Hispanic/Latino patients with obstructive lung disease had the lowest (7.42%; 95% CI 2.8%-12.05%). 5-year adjusted survival was highest among Hispanic/Latino patients (62.32%) compared to Black (57.59%) and White patients (57.82%).

CONCLUSIONS

There are significant differences in 1-year and 5-year mortality between and within racial and ethnic groups depending on gender and primary diagnosis. This demonstrates the impact of social and clinical factors on lung transplant outcomes.

Social and biologic determinants in lung transplant allocation

PURPOSE OF REVIEW

Lung transplant is a life-saving intervention for many with end-stage lung disease. As usable donor lungs are a limited resource and the risk of death on the waitlist is not uniform among candidates, organ allocation must consider many variables in order to be equitable.

RECENT FINDINGS

The lung allocation score (LAS) system, implemented in 2005, accounted for disease severity, risk of death without transplant, and 1-year survival estimates; however, recipient size, allosensitization, and blood type, biologic features that influence donor pool for a given recipient, do not impact allocation priority. Additionally, social determinants such as geography, socioeconomic status, race, and ethnicity can impact the likelihood of receiving a transplant. This has resulted in certain groups being transplanted at lower rates and at higher risk of dying on the waitlist. In order to address these disparities, lung organ allocation in the United States transitioned to a continuous distribution system using the composite allocation score (CAS) on 9 March 2023.

SUMMARY

In this article, we will review some of the data demonstrating the impact that biologic and social determinants have had on lung allocation in order to provide background as to why these have been incorporated into the CAS.

Addressing sex-based disparities in solid organ transplantation in the United States - a conference report

Solid organ transplantation provides the best treatment for end-stage organ failure, but significant sex-based disparities in transplant access exist. On June 25, 2021, a virtual multidisciplinary conference was convened to address sex-based disparities in transplantation. Common themes contributing to sex-based disparities were noted across kidney, liver, heart, and lung transplantation, specifically the existence of barriers to referral and wait listing for women, the pitfalls of using serum creatinine, the issue of donor/recipient size mismatch, approaches to frailty and a higher prevalence of allosensitization among women. In addition, actionable solutions to improve access to transplantation were identified, including alterations to the current allocation system, surgical interventions on donor organs, and the incorporation of objective frailty metrics into the evaluation process. Key knowledge gaps and high-priority areas for future investigation were also discussed.

Worsening racial disparity in waitlist mortality for pediatric heart transplant candidates since the 2016 Pediatric Heart Allocation Policy revision

BACKGROUND

The US Pediatric Heart Allocation Policy (PHAP) was revised in March 2016, with the goal of reducing waitlist mortality. We evaluated the hypothesis that these changes, which increased status exceptions, have worsened racial disparities in waitlist outcomes.

METHODS

Children in the Pediatric Heart Transplant Study database listed for first heart transplant from January 2012 - June 2020 were included and stratified by listing before (Era 1) or after (Era 2) the PHAP revision.

RESULTS

A total of 4,089 children were listed during the study period. Compared with white children (n = 2648), non-white children (n = 1441) were more likely to have an underlying diagnosis of cardiomyopathy in both eras. Waitlist mortality was similar in white and non-white children in Era 1, but comparatively worse for non-white children in Era 2. In multivariable analysis controlling for diagnosis, age, and severity markers, non-white children had a significantly higher waitlist mortality only in Era 2 (Era 1: sHR 1.22 [95%CI 0.90 - 1.66] vs. Era 2: sHR 1.57 [95%CI 1.17 - 2.10]).

CONCLUSIONS

Widening racial disparities in waitlist mortality may be an unintended consequence of the 2016 PHAP revision. Additional analyses may inform the degree to which this policy vs. unrelated changes in care differentially contribute to these disparities.

Human leukocyte antigen antibody sensitization, lung transplantation, and health equity

Women with advanced lung disease, particularly Black and Hispanic women, are more likely than other patients to have anti-human leukocyte (HLA) antibodies against potential donors. Sensitized patients, especially those who are highly sensitized, are less likely to be listed for lung transplant or to be considered candidates for mechanical circulatory support. They are also at higher risk for waitlist death. Institutional variability in approach to HLA antibody screening and pre-transplant management creates barriers to transplant that disproportionately impact Black and Hispanic women. At the same time, our understanding of the clinical significance of pre-transplant antibodies lags behind the sophistication of our screening assays. The lack of national data on pre- and post-transplant HLA antibody characteristics hinders research into strategies to mitigate concerns about these antibodies and to improve access to lung transplant among sensitized patients. Ongoing work should be done to identify clinically higher risk antibodies, to develop better strategies for safely crossing antibodies at the time of transplant, and to model changes in lung allocation to give priority to sensitized patients for a HLA antibody-antigen compatible donors. These priorities mandate a commitment to collaborative, multicenter research and to real time translation of results to clinical practice and allocation policy.

Racial disparities in cardiac transplantation: Chronological perspective and outcomes

BACKGROUND

The objective of this study was to evaluate annual heart transplant volumes and 3-year post-transplant outcomes since establishment of United Network for Organ Sharing (UNOS) database stratified by race.

METHODS

The UNOS thoracic transplant database was evaluated for adult patients since 1987. The available database was then stratified by Race: Black, White and Other and era of transplant: group 1(1987-1991), group 2(1992-1996), group 3(1997-2001), group 4(2002-2006), group 5(2007-2011), group 6(2012-2016) and group 7(2017 and later). Demographic and clinical factors were evaluated.

RESULTS

A total of 105,266 adults have been listed since 1987 and 67,824 have been transplanted. Of the transplanted patients 11,235 were Black, 48,786 White and 6803 were of Other race. The proportion of Black patients listed increased from 7% in 1987 to 13.4% in 1999 and 25% in 2019 and those transplanted increased from 5% in 1987 to 13.4% in 2001 and 26% in 2019. The survival of Black patients gradually improved.

CONCLUSION

Historically, fewer Black patients received cardiac transplantation however, their access gradually improved over the years and account for over 25% of cardiac transplantations performed in recent years. The historically poor survival of Black patients has recently improved and became comparable to the rest.