麻豆传媒

Hundreds of patients have received lung transplants due to COVID-19 in the U.S., with preliminary mortality rates looking on par with transplants for other reasons, a study showed.

Seven percent of lung transplants in United Network for Organ Sharing (UNOS) data -- 214 out of 3,039 from Aug. 1, 2020 through Sept. 30, 2021 -- were performed for respiratory failure due to COVID-19.

It's actually surprising that the proportion wasn't higher, said Joanna Chikwe, MD, of Cedars-Sinai Medical Center in Los Angeles, whose group reported the findings in a research letter in the .

"We were all concerned this might represent a much higher proportion of lung transplant patients," she told 麻豆传媒. "And this seems to have been through the worst of COVID, so hopefully this doesn't put unreasonable demands on the pool of lung transplant donors and deprive other patients of life-saving therapy."

While the median follow-up was only 1.9 months, the 30-day mortality rate was 2.2% (four deaths), and the 3-month survival rate was 95.6% (95% CI 90.1-98.1), which Chikwe called "really impressive."

The overall 3-month survival rate after lung transplantation was 93% in U.S. . The 1-year survival rate for lung transplant patients reached 88.8% before the pandemic, according to .

The similarity in survival rates "was the most surprising thing about this study," Chikwe said. "We fully expected, because these patients were so sick, that the mortality would be almost prohibitive after lung transplant."

A separate study of 30 lung transplants done for COVID-associated acute respiratory distress syndrome at Northwestern University in Chicago, published in , reported that all survived, with a median 351 days of post-transplant follow-up. By comparison, the survival rate was 83% for a contemporaneous group of 72 non-COVID lung recipients at the center.

Of the COVID cases at Northwestern, 57% were on extracorporeal membrane oxygenation (ECMO) before transplant compared with 1% of the non-COVID transplant recipients.

In Chikwe's data, the majority of transplants for COVID-19 patients followed mechanical ventilation (53.0%) and ECMO (64.5%), whereas the proportion requiring such support was in the single digits in the pre-pandemic UNOS data.

Nearly all transplants (92.1%) were bilateral lung transplants, including two heart-lung transplantations and five lung-kidney transplantations. In the UNOS data from 2019, 75.5% of lung transplants were bilateral.

Transplants in the U.S. had ground to a halt early in the pandemic before more than rebounding. Centers have reported good outcomes with donor lungs from decedents with a history of COVID-19, although a woman's death last year from COVID-19 contracted from the lungs she received from a donor not then known to be infected also stoked concern about testing protocols.

"Given the scarcity of lungs and given the demands on the ICU resources through COVID, was this use of resources justifiable? I think the clear message is a clear, absolute yes because these patients did remarkably well," Chikwe said.

Her group studied the UNOS registry data after the initial wave of the pandemic and found that, among the 64 centers that perform adult lung transplantations, the median number done for COVID-19-related respiratory failure was 2.5, but the range was up to 25.

More were done for acute respiratory distress syndrome (140 cases, 4.6% of the total transplantations) than for pulmonary fibrosis (74 cases, 2.4%). However, the latter group may grow over time, since patients who have recovered enough to get off the ventilator but have irreversible, severe pulmonary fibrotic changes due to superimposed infection and thromboembolic disease may progress to a stage in which they would need transplantation more electively, Chikwe noted.

COVID patients getting transplants looked different in a number of ways than the typical lung transplant population.

Not surprisingly for a disease for which there has been a male predominance in severe and fatal cases, lung transplants for COVID-19 occurred disproportionately in men, with 20.8% of recipients being women compared with 40% in the 2019 overall UNOS data for lung transplantation.

They were also younger (median age 52) and more likely to be Hispanic (37% vs the usual ~10%).

Limitations to the study included incomplete data on how long lung recipients had been on ventilation or circulatory support before transplantation, whether they had been vaccinated for COVID beforehand, and what their COVID testing showed at the time of transplant.

More importantly, "short-term follow-up precludes firm conclusions about the longer-term usefulness of lung transplantation in this context," Chikwe's group cautioned.

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