Amid Scant Data, Lung Transplant Disparities Persist

Evidence that White patients with lung disease are disproportionately more likely to get a lung transplant compared with minority populations hasn’t shifted much in recent years. And while pulmonology transplant experts acknowledge multiple challenges moving toward a more equitable donor lung allocation strategy that overcomes racial, ethnic, and socioeconomic disparities, they also noted that nascent widespread efforts to improve lung transplant data collection and preserve donor lungs and donor lung distribution could address those inequities.

Where Are the Data?

But getting detailed data on lung transplants and who gets them has been an ongoing challenge, Holly Keyt, MD, lung transplant director at the University of Texas Health San Antonio, said. “Research in this area is lacking,” Keyt told Medscape Medical News. “It’s something we as the pulmonary community and we as the transplant community need to come together to understand better.”

That people at the low end of the socioeconomic spectrum are less likely to get a lung transplant is well known, if not well documented, she said. Studies have been done in specific patient populations, such as idiopathic pulmonary fibrosis and cystic fibrosis, Keyt said, “but a lot of referral data is lacking because we don’t have a large registry that captures that. A lot of the data we have come from the registry of patients who actually go through the evaluation recess.”

Keyt noted that a symposium of transplant experts held before this year’s International Society of Heart Lung Transplantation meeting in Prague tackled improving data collection on lung transplantation, possibly even creating a registry. “Hopefully out of that is going to come more work,” she said.

That lack of data has made it difficult to get a clear picture of disparities among lung transplant recipients, Keyt said. A recent study in the Journal of the American Medical Association identified race and gender disparities in heart transplants, but no parallel study exists for lung transplants.

A 2022 National Academy of Sciences, Engineering, and Medicine (NASEM) report reported that almost 2800 lung transplants were performed in the United States in 2019, increasing more than 50% in the previous decade. At the same time, the number of donor lungs increased by 62%.

The NASEM report “found that the organ transplantation system was demonstrably inequitable,” the report’s chair, Kenneth Kizer, MD, distinguished professor emeritus in emergency medicine at the University of California Davis School of Medicine in Sacramento, said in an interview.

“Most of the same factors that contribute to inequities or disparities in organ transplantation broadly also contribute to disparities in lung transplantation,” Kizer said. “These factors include minority race, low socioeconomic status, living in rural or other medically underserved areas, lack of health insurance, intellectual disability, and lack of family or other social support.”

A 2021 study identified sex, race, geographic, and age disparities in both heart and lung transplantation but did not separate the two. Another 2020 study reported on geographic disparities for lung transplant access. This study found that people with an associate’s degree or higher were more likely to seek out a high-volume center, but it found no survival difference between patients who stayed at their home hospital and those who went to an alternative institution.

Keyt noted that a 2021 study of patients with advanced cystic fibrosis lung disease found that those in the United States had a 79% greater risk for death without a lung transplant and a 34% lower likelihood of getting a lung transplant than similar patients in Canada.

Meanwhile, in the United States, overall lung transplant survival rates are stagnant, Kizer said. The Health Resources and Services Administration Scientific Registry of Transplant Recipients 2021 Annual Data Report found that 85.3% of transplant recipients survive to 1 year, but only a half — 54.3% — make it to 5 years and less than a third — 32.8% — to 10 years. “More recent data is not notably different,” Kizer said.

Continuous Distribution

One potential strategy to address disparities in lung transplants is a concept known as continuous distribution, noted Wayne Tsuang, MD, PhD, who specializes in pulmonary, critical care, and transplant medicine at Case Western Reserve University and Cleveland Clinic in Cleveland and has studied disparities in transplantation. The Organ Procurement and Transplantation Network implemented a lung continuous distribution policy in 2023.

“The goal of the new system is to increase the efficiency of donor lung allocation and reduce the role of geography in matching wait-listed patients with donor lungs,” Tsuang said. Continuous distribution generates a Composite Allocation Score for each wait-listed patient. “This new score determines where a patient is on the wait-list and includes many attributes, which were not accounted for previously, such as biologic characteristics including height or blood type as well as travel distance from donor hospital to recipient hospital.”

Preserving More Donor Lungs

Other advances have the potential to increase the pool of donor lungs viable for transplantation. “At present, only about 15%-20% of donor lungs are considered viable for transplantation,” Kizer said. “A number of circumstances may make a donated lung not suitable for transplantation, including the lung’s susceptibility to injuries from excess fluid accumulation, bacterial infection, or complications from the donor’s preterminal medical care.”

One such advance Kizer noted is ex vivo lung perfusion in which the lung is connected to a ventilator, pump, and filters inside a sterile plastic dome, which perfuses the organ with an acellular solution containing nutrients, proteins, and a mix of oxygen, carbon dioxide, and nitrogen. “These combined procedures have been shown to reduce posttransplantation rejection and to improve patient posttransplant survival rates to those comparable to transplants with less physiologically stressed or non-compromised organs,” Kizer said.

At the International Society of Heart Lung Transplantation meeting in April, Pedro Catarino, MD, director of aortic surgery at Cedars-Sinai Medical Center in Los Angeles, reported on another technique to increase the number of viable donor lungs. Thoracoabdominal normothermic regional perfusion (TA-NRP) perfuses blood through a donor’s abdomen and chest after the heart has stopped beating for up to 40 minutes to reanimate the heart and ventilate the lungs. Catarino presented data showing that the retrieval rate for donation after circulatory death lungs has increased to about 15% with the utilization of TA-NRP. However, some lung experts harbor concerns that lungs are injured during the in situ perfusion process.

Ongoing innovations in technology can also help reduce disparities, Tsuang said. “Examples include the wider implementation of telehealth for follow-up patient care or the use of new blood tests, which can detect complications after lung transplant instead of having to do a more invasive lung biopsy,” he said. “These innovations streamline and simplify the care of transplant recipients, and in doing so, enable transplant care to be offered to a broader population and therefore contribute towards a reduction in disparities.”

Keyt, Kizer, and Tsuang had no relevant financial relationships to disclose.

Richard Mark Kirkner is a medical journalist based in the Philadelphia area.