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OPTN/SRTR 2022 Annual Data Report: Lung

OPTN/SRTR 2022 Annual Data Report: Lung

Maryam Valapour1,2, Carli J. Lehr2, David P. Schladt1, Jodi M. Smith1,3, Kaitlin Swanner4, Chelsea J. Weibel4, Samantha Weiss4, Jon J. Snyder1,5,6

1Scientific Registry of Transplant Recipients, Hennepin Healthcare Research Institute, Minneapolis, MN

2Department of Pulmonary Medicine, Respiratory Institute, Cleveland Clinic, Cleveland, OH

3Department of Pediatrics, University of Washington, Seattle, WA

4Organ Procurement and Transplantation Network, United Network for Organ Sharing, Richmond, VA

5Department of Epidemiology and Community Health, University of Minnesota, Minneapolis, MN

6Department of Medicine, Hennepin Healthcare, University of Minnesota, Minneapolis, MN

Abstract

For the first time since the COVID-19 pandemic, the annual number of lung transplants performed in the United States increased. The year 2022, encompassed in this report, marks the last full calendar year where the Lung Allocation Score was used for ranking transplant candidates based on their estimated transplant benefit and donor lung allocation in the United States. In March 2023, a major change in transplant allocation policy occurred with the implementation of the Composite Allocation Score. Transplant rates have increased over the past decade, although there is variability among age, diagnosis, racial and ethnic, and blood groups. Over half of candidates received a lung transplant within 3 months of placement on the waiting list, with nearly 75% of candidates accessing transplant by 1 year. Pretransplant mortality rates remained stable, with approximately 13% of lung transplant candidates dying or being removed from the waiting list within a year of listing. Posttransplant survival remained stable; however, variability exists by age, diagnosis, and racial and ethnic groups.

Keywords: End-stage lung disease, Lung Allocation Score, lung transplant, organ allocation, transplant outcomes

1 Introduction

In the year 2022, there were 2,743 lung transplants performed in the United States, representing an increase of 174 lung transplants from 2,569 in 2021 (Figure LU 44). The number of lung transplants performed did not reach the pre–COVID-19 pandemic national transplant volumes noted in 2019. The number of new adult candidates added to the waiting list annually continued to increase following the nadir noted in 2020, with 3,161 candidates added in 2022 (Figure LU 1).

Data from 2022 must be understood in the context of related policy changes. Lung allocation policy changes were implemented on September 30, 2021, to prepare for the eventual implementation of the Composite Allocation Score system, which occurred on March 9, 2023. The changes on September 30, 2021, affected the Lung Allocation Score (LAS) calculation and reflected an updated candidate and recipient cohort to improve the predictions of the waitlist and posttransplant mortality models used to calculate the LAS. Multiple variables were removed from the LAS risk models, including the diagnoses of obliterative bronchiolitis, lymphangioleiomyomatosis, and Eisenmenger syndrome; bilirubin increase of 50% or greater; diabetes; forced vital capacity; cardiac index; and central venous pressure from the waitlist survival model. The variables for functional status; creatinine increase of at least 150%; and the diagnoses of lymphangioleiomyomatosis, Eisenmenger’s syndrome, and “pulmonary fibrosis, other” were removed from the posttransplant survival model. The remaining variable parameterizations were updated to reflect the updated candidate and recipient cohorts. The LAS in use in 2022 continued to use a 2:1 ratio of 1-year waitlist and 1-year posttransplant survival estimates.

The LAS used waitlist and posttransplant mortality models to estimate transplant benefit and was used to rank candidates aged 12 years and older for transplant after accounting for geography, blood type, size compatibility, and HLA antibodies. Pulmonary diseases were characterized into four main diagnosis groups in the system: group A, obstructive lung disease; group B, pulmonary vascular disease; group C, cystic fibrosis and immunodeficiency disorders; and group D, restrictive lung diseases. These groupings were derived to aggregate individuals based on disease pathophysiology and survival probability. Allocation system changes that must be taken into consideration when interpreting longitudinal data in this report include: 1) the 2015 update using a contemporary cohort and new variables for group B candidates; 2) the 2017 update that changed the first unit of allocation to a 250–nautical-mile radius from the donor hospital; and 3) the 2021 update using a contemporary cohort, updated variable parameterizations, and with fewer variables in the waitlist and posttransplant mortality models. Allocation rules differed for individuals younger than 12 years and were determined by geography, age, blood-type compatibility, illness-based priority status, and waiting time.

The Adult Lung Transplantation section in this report includes information on all lung transplant candidates and recipients aged 18 years or older at the time of placement on the waiting list. The Pediatric Lung Transplantation section includes information on all lung transplant candidates and recipients younger than 18 years at the time of placement on the waiting list. Reports from 2019 and earlier separated adult and pediatric sections at the age of 12 years, but this was changed in 2020 to align with international reporting. This chapter includes data on all US lung and heart-lung candidates and transplant recipients.

2 Adult Lung Transplantation in the United States

2.1 Waiting List

2.1.1 Characteristics of adult candidates listed for lung transplant

In 2022, there were 3,161 candidates added to the lung transplant waiting list (Figure LU 1). There were 4,228 candidates on the lung transplant waiting list during the year, a number which has remained relatively constant since 2011 (Figure LU 2). In 2022, 6.0% of candidates were aged 18-34 years, 12.8% were 35-49 years, 44.2% were 50-64 years, and 36.9% were 65 years or older. The percent of candidates aged 65 years or older increased by 63.5% while the percent of candidates aged 18-34 years decreased by 50.2% from years 2011 to 2022 (Figure LU 3). In terms of sex distribution, 44.7% of waitlist candidates were women, with an overall decrease of 13.7% in female candidates since 2011 (Figure LU 4). The proportion of candidates by self-identified racial and ethnic group has remained relatively stable since 2021. In 2022, 4.8% of candidates identified as Asian, 11.3% as Black, 14.7% as Hispanic, and 68.4% as White. However, changes have emerged over time, with an increase of 163.8% Asian, 18.0% Black, and 153.2% Hispanic candidates and a decrease of 16.7% White candidates since 2011 (Figure LU 5). The proportion of candidates in group D continued to increase, representing 69.1% of the waiting list in 2022, while group A candidates decreased to 20.6%, and group C has decreased to only 1.8% of the waitlist population (Figure LU 6).

The proportion of candidates with the lowest LAS values (<35) decreased from 34.9% in 2011 to 22.8% in 2022, while those with the highest LAS values (60 or greater) have increased from 14.0% in 2011 to 22.9% in 2022 (Figure LU 8). Trends in candidate height ranges remained stable, with 3.3% of candidates < 150 cm and 16.8% of candidates > 180 cm (Figure LU 9). For ABO blood type, the greatest proportion of transplant candidates had type O blood (49.0%), followed by type A (36.5%), type B (11.6%), and type AB (2.9%) (Figure LU 10). The proportion of candidates who were awaiting a retransplant remained stable at 3.2% (Figure LU 11).

2.1.2 Outcomes of adult candidates listed for lung transplant

Transplant rates continued to climb, with a 148.3% increase since 2011 for a transplant rate of 258.7 lung transplants per 100 patient-years; the greatest increase was for candidates aged 65 years or older (Figure LU 12, Figure LU 13). Lung transplant rates were lowest for Black candidates at 184.8 transplants per 100 patient-years compared with a range of 223.5-278.2 transplants per 100 patient-years for candidates of other racial and ethnic groups (Figure LU 14). Transplant rates were expectedly highest for candidates in diagnosis group D at 339.4 transplants per 100 patient-years and lowest for those in diagnosis group C at 140.4 transplants per 100 patient-years (Figure LU 15). Transplant rates were highest for those with blood type AB at 445.2 transplants per 100 patient-years (Figure LU 16). Those of the shortest stature had the lowest transplant rates, with sequential increases across candidate height (Figure LU 17).

Most candidates (61.4%) spent less than 90 days on the waiting list, 13.9% spent 3-<6 months on the waiting list, 12.2% spent 6-12 months on the waiting list, and 12.5% spent 1 year or longer on the waiting list (Figure LU 7). By 1 year on the waiting list, 74.5% of candidates underwent a deceased donor transplant, 12.2% remained on the list, 5.7% died, and 7.6% were removed from the list (Figure LU 18). Pretransplant mortality rates have remained relatively stable at 18.8 deaths per 100 patient-years, but trends by age have varied over time with increases in mortality rates over the past year for individuals aged 18-34 and 35-49 years (Figure LU 20, Figure LU 21). Pretransplant mortality rates were higher for men (23.0 deaths per 100 patient-years) compared with women (15.8 deaths per 100 patient-years) (Figure LU 23). Pretransplant mortality rates were highest for group D, followed by groups B, A, and C, respectively (Figure LU 24). As expected, pretransplant mortality rates were consistent with LAS values; that is, those with higher LAS values had higher pretransplant mortality (Figure LU 25). Blood groups A and O had the lowest pretransplant mortality rates while group AB had the highest (Figure LU 26). Pretransplant mortality rates were highest for those 180 cm or taller followed closely by those < 150 cm, with individuals 150-<180 cm in height trending closely together (Figure LU 27). Of candidates removed from the waiting list for reasons other than transplant or death, 23.2% died within 6 months, with the highest rates for diagnosis groups B and D and for older candidates, but with similar rates by sex and racial and ethnic groups (Figure LU 28, Figure LU 29, Figure LU 30, Figure LU 31, Figure LU 32).

2.2 Donors

The year 2022 had the highest number of deceased donors at 2,852, representing a 62.4% increase since 2011 (Figure LU 33). The distribution of donor age was as follows: younger than 18 years, 6.3%; 18-29 years, 28.4%; 30-39 years, 26.5%; 40-54 years, 26.9%; and 55 years or older, 11.9% (Figure LU 34). The proportion of donors remained stable by sex, with 60.3% male donors, and by race and ethnicity, with 59.3% White donors followed by 18.9% Black donors and 17.4% Hispanic donors (Figure LU 35, Figure LU 36). The nonuse rate (lungs recovered for transplant and not transplanted) has risen over time, from 4.2% in 2011 to 9.0% in 2022 (a 112.1% increase), with the highest nonuse rate of 14.0% for donors aged 55 or older (Figure LU 37, Figure LU 38). Nonuse rates did not differ meaningfully by sex (Figure LU 39), but differences by race and ethnicity exist, with the highest rates of nonuse for Black and White donors and with lower rates for Hispanic and Asian donors (Figure LU 40). Nonuse rates differed by donor cause of death, with the highest rates for causes of death including anoxia and cerebrovascular accident/stroke (Figure LU 41). Standard-risk donor lungs had higher rates of nonuse (9.5%) compared with US Public Health Service increased-risk donors (6.9%) (Figure LU 42). In 2022, anoxia was the most common cause of donor death, followed by head trauma, cerebrovascular accident/stroke, and other/unknown causes (Figure LU 43). The use of donation after circulatory death donors increased from 3.7% in 2017 to 7.4% in 2022 (Table LU 8).

2.3 Transplant

2.3.1 Characteristics of lung transplant recipients

In 2022, there were 2,743 lung transplants (adult and pediatric) performed and, of these, 2,196 (80.0%) were bilateral transplants (Figure LU 44, Figure LU 45). By age, there were 21 transplants performed in recipients younger than 18 years; 125, in those aged 18-35 years; 307, in those aged 35-49 years; 1,168, in those aged 50-64 years; and 1,112, in those aged 65 years and older (Figure LU 46). There were 1,701 male and 1,042 female transplant recipients (Figure LU 47). By racial and ethnic groups, 1,939 transplant recipients were White; 402, Hispanic; 257, Black; 123, Asian; 15, Native American; and 7, Multiracial (Figure LU 48). The greatest number of transplants occurred for individuals in group D at 2,031, followed by 498 transplants in group A, 168 in group B, and 46 in group C (Figure LU 49). For recipients with an LAS of 35 or less, 35-<40, 40-<50, 50-<60, and 60 or greater, the number of transplants that occurred were 480, 597, 698, 259, and 701, respectively (Figure LU 50). The percentage of adult candidates supported with extracorporeal membrane oxygenation (ECMO) continued to increase, from 5.2% in 2017 to 8.7% in 2022 (Table LU 7).

2.3.2 Outcomes of adult lung transplant recipients

Induction was used in 86.8% of transplant recipients, while 82.5% received subsequent immunosuppression with tacrolimus, mycophenolate mofetil, and a steroid agent (Figure LU 51, Figure LU 52). Notably, rates of acute cellular rejection in the first year have decreased over time with similar rates by racial and ethnic groups (Figure LU 62). The incidence of posttransplant lymphoproliferative disorder is 1.8% by 5 years, with variation by recipient Epstein-Barr virus status (Figure LU 63). For transplants performed in 2021, 1-year post-transplant mortality was 12.2%, and for transplants performed in 2017, 5-year posttransplant mortality was 40.4% (Figure LU 53). Transplant recipients aged 35-49 years had the highest survival and those aged 65 years or older had the lowest survival by 5 years posttransplant (Figure LU 55). By 5 years posttransplant, survival differed across racial and ethnic groups, with those of Hispanic ethnicity having the greatest survival followed by those of White, Black, Asian, Multiracial, and Native American racial groups (Figure LU 56). By 5 years, survival by LAS group only differed by 6.04%: 62.6% for the 35-or-less LAS group and 56.5% for the 60-or-greater group (Figure LU 57). Percent survival for bilateral transplant was higher by 6 months posttransplant compared with single transplant, but it is important to acknowledge that this is an unadjusted analysis and does not consider potential confounders in procedure selection and candidate condition at time of listing and transplant (Figure LU 58). Percent survival differed by diagnosis group at 5 years, with the highest percent survival for those in diagnosis group C and the lowest in diagnosis group D, an effect likely affected by recipient age (Figure LU 59).

3 Pediatric Lung Transplantation in the United States

3.1 Waiting List

3.1.1 Characteristics of pediatric candidates listed for lung transplant

In 2022, 47 new pediatric candidates (younger than 18 years at listing) were added to the lung transplant waiting list, a 49% decrease from 92 new listings in 2011 (Figure LU 64). The total number of pediatric waitlist candidates decreased by 67.0%, from 221 in 2011 to 73 in 2022 (Figure LU 65). The largest age group of pediatric candidates on the waiting list continues to be the 12- to 17-year cohort (52.1%), followed by other age groups: 6-11 years (24.7%), 1-5 years (15.1%), and younger than 1 year (5.5%) (Figure LU 66). By race and ethnicity, the highest percentage of pediatric lung transplant candidates were White (46.6%), followed by Hispanic (28.8%), Black (13.7%), Asian (8.2%), and Multiracial (2.7%) (Figure LU 67). Looking at changes over time, the proportions of Asian, Black, Hispanic, and Multiracial candidates have increased since 2011 while the proportion of White candidates has decreased. Pediatric candidates who have been on the list fewer than 90 days represent the highest proportion (41.1%) in terms of waiting time (Figure LU 69). The etiology of lung disease among pediatric candidates has changed over time, with a decrease in the proportion of candidates with cystic fibrosis from 40.0% in 2017 to 9.7% in 2022 (Table LU 10).

3.1.2 Outcomes of pediatric candidates listed for lung transplant

Of 42 candidates removed from the waiting list in 2022, 22 (52.4%) were removed after undergoing transplant; 7 (16.7%), due to patient death; 2 (4.8%), due to becoming too sick to undergo transplant; 1 (2.3%), after refusing transplant; and 10 (23.8%), for other reasons (Table LU 12, Table LU 13). Among pediatric lung transplant candidates listed in 2017-2019, 64.1% underwent deceased donor transplant within 3 years, 20.6% were removed from the list for reasons other than transplant or death, 14.4% died waiting, and 1.0% were still waiting (Figure LU 70). The overall pediatric lung transplant rate has decreased to 76.8 transplants per 100 patient-years in 2022, from a peak of 150.3 transplants per 100 patient-years in 2019 (Figure LU 71). Transplant rates varied with age and were highest for pediatric candidates aged 12-17 years (137.8 transplants per 100 patient-years), followed by candidates younger than 1 year (92.8 per 100 patient-years), 6-11 years (39.3 per 100 patient-years), and 1-5 years (32.6 per 100 patient-years) (Figure LU 72). Transplant rates also varied by race and ethnicity, with the highest rates among those in the “Other” category, likely due to the small size of the group (317.4 transplants per 100 patient-years), followed by Asian candidates (140.4 per 100 patient-years), Hispanic candidates (92.6 per 100 patient-years), White candidates (67.4 per 100 patient-years), and Black candidates (44.5 per 100 patient-years) (Figure LU 73). Pretransplant mortality was 20.6 per 100 patient-years in 2022, down from a peak of 42.9 deaths per 100 patient-years in 2015 (Figure LU 74). Pretransplant mortality varied by age: 46.4 deaths per 100 patient-years among candidates aged younger than 1 year, zero among candidates aged 1-5 years, 37.8 deaths per 100 patient-years among candidates aged 6-11 years, and 14.6 deaths per 100 patient-years among candidates aged 12-17 years (Figure LU 75).

3.2 Transplant

3.2.1 Characteristics of pediatric lung transplant recipients

In 2022, 21 lung transplants were performed in pediatric recipients aged 0-17 years at the time of listing, a decrease of 53% since 2011 when there were 45 transplants (Figure LU 76): one in those younger than 1 year, three in those aged 1-5 years, four in those aged 6-11 years, and thirteen in those aged 12-17 years (Figure LU 77). As seen in the waitlist candidate characteristics, there has been a change in the etiology of lung disease among pediatric transplant recipients, with a decrease of the proportion of recipients with cystic fibrosis from 55.6% in 2017 to only 19% in 2022 (Table LU 15). In 2022, almost 40% of pediatric recipients were bridged to transplant (in contrast to 10.5% of adult recipients): 19.0% required mechanical ventilation and ECMO; 14.3%, mechanical ventilation only; and 4.8%, ECMO only (Table LU 15). Induction therapy was reported in 81.0% of pediatric lung transplant recipients in 2022 (Figure LU 78). The most common initial immunosuppression regimen was tacrolimus, mycophenolate, and steroids, reported in 66.7% of pediatric lung recipients (Figure LU 79). There appears to have been a shift over time, with a 16.7% decrease in this triple immunosuppression regimen, from 80% in 2011 to 66.7% in 2022; a 114.3% increase in the tacrolimus and mycophenolate mofetil combination, from 4.4% in 2011 to 9.5% in 2022; and a 221% increase in the tacrolimus-steroid regimen, from 4.4% in 2011 to 14.3% in 2022 (Figure LU 79).

3.2.2 Outcomes of pediatric lung transplant recipients

Across all pediatric recipients who underwent lung transplant in 2015-2017, 1-, 3-, and 5-year patient survival were 84.4%, 64.8%, and 56.3%, respectively (Figure LU 82). Incidence of death was 16.0% at 6 months and 16.0% at 1 year for transplants in 2021, 36.5% at 3 years for transplants in 2019, 48.9% at 5 years for transplants in 2017, and 55.9% at 10 years for transplants in 2012 (Figure LU 81). The incidence of posttransplant lymphoproliferative disorder among Epstein-Barr–negative recipients who underwent transplant in 2011-2017 was 7.1% at 5 years posttransplant, compared with 1.9% among Epstein-Barr–positive recipients (Figure LU 80).

List of Figures

List of Tables




**New adult candidates added to the lung transplant waiting list.** A new adult candidate is one who first joined the list during the given year, without having been listed in a previous year. Previously listed candidates who underwent transplant and subsequently relisted are considered new. Active and inactive patients are included.

Figure LU 1: New adult candidates added to the lung transplant waiting list. A new adult candidate is one who first joined the list during the given year, without having been listed in a previous year. Previously listed candidates who underwent transplant and subsequently relisted are considered new. Active and inactive patients are included.




**All adult candidates on the lung transplant waiting list.** Adult candidates on the list at any time during the year. Candidates listed at more than one center are counted once per listing.

Figure LU 2: All adult candidates on the lung transplant waiting list. Adult candidates on the list at any time during the year. Candidates listed at more than one center are counted once per listing.




**Distribution of adults waiting for lung transplant by age.** Candidates waiting for transplant at any time in the given year. Candidates listed at more than one center are counted once per listing. Active and inactive candidates are included. Age is determined at the earliest of transplant, death, removal, or December 31 of the year.

Figure LU 3: Distribution of adults waiting for lung transplant by age. Candidates waiting for transplant at any time in the given year. Candidates listed at more than one center are counted once per listing. Active and inactive candidates are included. Age is determined at the earliest of transplant, death, removal, or December 31 of the year.




**Distribution of adults waiting for lung transplant by sex.** Candidates waiting for transplant at any time in the given year. Candidates listed at more than one center are counted once per listing. Active and inactive patients are included.

Figure LU 4: Distribution of adults waiting for lung transplant by sex. Candidates waiting for transplant at any time in the given year. Candidates listed at more than one center are counted once per listing. Active and inactive patients are included.




**Distribution of adults waiting for lung transplant by race and ethnicity.** Candidates waiting for transplant at any time in the given year. Candidates listed at more than one center are counted once per listing. Active and inactive patients are included.

Figure LU 5: Distribution of adults waiting for lung transplant by race and ethnicity. Candidates waiting for transplant at any time in the given year. Candidates listed at more than one center are counted once per listing. Active and inactive patients are included.




**Distribution of adults waiting for lung transplant by diagnosis group.** Candidates waiting for transplant at any time in the given year. Candidates listed at more than one center are counted once per listing. Active and inactive patients are included. The unknown group includes a small number of heart-lung candidates prior to 2015 who did not have an A/B/C/D diagnosis group specified.

Figure LU 6: Distribution of adults waiting for lung transplant by diagnosis group. Candidates waiting for transplant at any time in the given year. Candidates listed at more than one center are counted once per listing. Active and inactive patients are included. The unknown group includes a small number of heart-lung candidates prior to 2015 who did not have an A/B/C/D diagnosis group specified.