麻豆传媒

NASHVILLE, Tenn. -- Expanding the selection criteria for extracorporeal membrane oxygenation (ECMO) as a bridge to lung transplant to include older and sicker patients was not associated with worse survival, a retrospective cohort study showed.

Other studies presented here during the "Lung Transplantation: New Issues in 2022" session at , the annual meeting of the American College of Chest Physicians, included one on sociodemographic trends in lung transplant in the U.S. from 2001 through 2021, and two presentations on COVID-19 in lung transplant recipients.

ECMO As a Bridge to Lung Transplant

Between patients who met the standard ECMO-bridge criteria and those who met the extended criteria, there were no significant differences in the odds of receiving a transplant, being delisted or dying on the transplant waitlist, surviving to 1-year post-transplant, or surviving to hospital discharge, reported Abdul Wahab, MBBS, of the Mayo Clinic in Rochester, Minnesota, during the session.

The most common reasons that patients did not meet standard selection criteria included age older than 55 years, use of prednisone 10-20 mg/day, inability to participate in physical therapy or to achieve a 6-minute walk distance of less than 200 meters, a body mass index greater than 30 or less than 18.5, and heart, renal, or other non-pulmonary organ dysfunction.

Wahab noted that the ECMO to transplant rate among all patients in the study was around 56% (53% in the expanded criteria group), which he said was comparable to other transplant centers that follow strict institutional criteria for ECMO as a bridge to lung transplant.

"No significant differences [between the traditional and expanded criteria group] were observed in 1-year post-transplant survival and there was no difference in 6-minute walk distance," he noted. "So patients who deviate from traditional selection criteria can have similar outcomes if they are offered ECMO as a bridge therapy to transplant."

More rigid traditional selection criteria may limit the opportunity for transplant among patients who might have few other treatment options, he added.

This analysis included 45 patients put on ECMO as a bridge to lung transplant or transplant consultation at the Mayo Clinic in Rochester or Florida from 2009 through mid-2021, including 15 patients who met traditional selection criteria and 30 who had risk factors that placed them in the expanded criteria category.

Sociodemographic Trends in Lung Transplant

Looking at data from the Organ Procurement and Transplantation Network (OPTN) registry, Paras Malik, MD, of the Jacobi Medical Center in the Bronx, New York, reported on findings from a population-based study on sociodemographic trends in lung transplantation in the U.S. over the last two decades.

They found that lung transplants increased from 1,059 in 2001 to 2,524 in 2021. The only significant decline in transplants during this period was during COVID-19 lockdowns, Malik said.

Emphysema/chronic obstructive pulmonary disease was the most common indication for lung transplant in 2001, while idiopathic pulmonary fibrosis was the most common in 2021, accounting for 889 of the transplants that year.

During both time points, adults ages 50 to 64 had the most lung transplants of any age group (46% and 58% of transplants, respectively, in 2001 and 2021), but the proportion of patients over the age of 65 increased dramatically, from 3.4% in 2001 to around 37% in 2021, Malik noted.

Most lung transplant recipients were white (88% in 2001 and 70% in 2021), though the proportions of Black, Asian, and Hispanic adults receiving transplants increased by 2%, 3.3%, and 11.8%, respectively, over this time period.

"Most of the people who register for and undergo transplants are still predominantly white," Malik said, adding that expanding access to lung transplant will require addressing ongoing disparities in equitable healthcare delivery.

COVID-19 in Lung Transplant Recipients

In an analysis involving 28 patients who underwent lung transplant at a single large center and developed COVID-19-related pneumonia prior to June 2021, the overall mortality rate was 21%, with 68% of patients admitted to the hospital. The mortality rate among hospitalized patients who required treatment in the intensive care unit (ICU) was 62%, reported Love Patel, MD, of Loyola Medicine in Chicago.

He noted that there was no statistically significant change in lung function, as measured by forced expiratory volume (FEV₁), observed pre- and post-COVID. However, compared with survivors, patients who died had a lower average pre-COVID FEV₁ (1.32 L, P<0.037).

None of the patients developed new-onset chronic lung allograft dysfunction (CLAD).

In another presentation, Gayathri Sathiyamoorthy, MD, of the Richard DeVos Heart & Lung Transplant Program in Grand Rapids, Michigan, reported that 19% of 219 lung transplant recipients at his center developed COVID from March 2020 to December 2021.

Most of these patients were on standard three-drug immunosuppressive regimens at the time of their diagnosis, and 11 required hospitalization.

Four required ICU admission and intubation, and three died (3, 16, and 26 days from infection).

Sathiyamoorthy noted that this mortality rate is lower than rates typically seen at other transplant centers, which she attributed to vaccine availability later in the study period and early SARS-CoV-2 detection through close patient monitoring.

She added that additional studies are needed to better understand COVID's impact on lung transplant recipients, with a focus on exploring effects on risk for transplant rejection and CLAD.

Todd Grazia, MD, of the Baylor University Medical Center in Dallas, agreed.

"We know that mortality was high in this patient population early in the pandemic, but there is a lot we still don't know," he told 麻豆传媒. "We need more data to truly understand COVID's impact on transplant in the pre- and post-vaccine periods and during the Alpha-, Delta-, and now Omicron-predominant periods."