COPD-Related Lung Transplantation: How Can We Improve Survival Rates?

Chronic obstructive pulmonary disease (COPD) is the leading indication for lung transplantation globally, and the second indication in the United States. Despite this, a lack of consensus remains regarding the timing and types of transplant surgery.¹

“One of my goals with [our research] was to educate the pulmonary community on the role of transplant for patients with COPD, both the potential benefits and the potential risks,” acknowledged Joshua M. Diamond, MD, MSCE, associate medical director, Lung Transplantation Program and assistant professor of medicine at the Hospital of the University of Pennsylvania in Philadelphia and coauthor of a review recently published in Current Opinion in Pulmonary Medicine. “I often find that COPD patients come to see us for transplant consideration without being informed of some of the basics, and therefore are disappointed when we present the limits — unclear survival benefit being the most prominent one.”

To be eligible for transplant surgery, patients must be placed on a waiting list, which involves a complex algorithm to assess priority.¹ One of the main tools to assess medical urgency is the lung allocation scoring, which is based on age, lung function, body mass index, diabetes, and disease severity.² Because patients with COPD have a variable disease trajectory, it may be difficult for clinicians to decide when to place a patient on the lung transplant surgery waiting list.¹

By the time patients get on a waiting list, they are often deemed ineligible because of poor overall health and frailty.³ Aimee M. Layton, PhD, RCEP, cardiopulmonary laboratory director at Columbia University Medical Center in New York City, and colleagues sought to determine how frailty influences exercise tolerance. In a study of 68 patients (mean age, 57 years), frail patients’ exercise tolerance was 38 W lower (95% CI, 18.4-58.1 W), and their peak aerobic capacity was 8.5 mL/kg/min lower (95% CI, 3.3-13.7 mL/kg/min), compared with patients who were not frail. Independent of disease severity, frailty contributes to lower exercise tolerance in patients awaiting lung transplants.³

“More research is needed to determine if there is a threshold in physical debilitation that predicts a substantial risk [for] perioperative death or complications with the surgery for the listing criteria to change,” noted Dr Layton. “However, our research helps to provide data that guides such future research to which variables they should be testing to predict such outcomes. As of right now, the current listing criteria recommend that patients are enrolled in pulmonary rehabilitation while awaiting lung transplant to improve and maintain a level of physical vigor while awaiting transplant. However, it is questionable how many patients are actually attending programs and the availability of pulmonary rehabilitation programs.”

Waiting List: Time for Improvement

The International Society for Heart and Lung Transplantation (ISHLT) recommends prioritizing patients according to the BODE index, which incorporates body mass index, obstruction, dyspnea, and exercise capacity.⁴ Such an assessment tool could potentially disadvantage patients with COPD who typically have comorbidities such as cardiovascular disease and cancer that could render them ineligible for transplant surgery.⁴

To test this hypothesis, Robert M. Reed, MD, associate professor at the University of Maryland School of Medicine in Baltimore, and colleagues performed a retrospective chart analysis of patients with COPD from 2 cohorts: the United Network for Organ Sharing (UNOS; n=4377) and those stratified by the BODE score (n=625).⁴ Patients in the fourth quartile of the BODE score UNOS cohort had a median survival of 59 months (95% CI, 51-77 months), and those in the BODE validation cohort survived a median 37 months (95% CI, 29-42 months).⁴ The subhazard ratio for death risk in the BODE validation cohort was 4.8 (95% CI, 4.0-5.7; P <.001).⁴ Researchers concluded that the BODE score may overestimate the mortality risk in patients with COPD because it does not take comorbidities into consideration.