Column: Lung Transplants; Objective Fairness vs. The Wisdom of Solomon
Concerns have been raised about the plight of Sarah Murnaghan, a 10-year-old girl dying of cystic fibrosis and awaiting a lung transplant in Philadelphia. I would like to correct some of the misconceptions about the lung allocation system and how it pertains to children, and offer some suggestions.
Lung disease is the third-leading cause of death in the United States. Lung transplantation improves survival and quality of life for patients suffering from end-stage lung disease, but it is severely constrained by a shortage of suitable lungs from conventional organ donors — people who are intubated and ventilated after a lethal brain injury that progresses to brain death. Most conventional organ donors’ lungs are not usable for transplant because of pulmonary edema caused by brain injury, or aspiration pneumonia after a head injury.
For five years, I headed the Lung Allocation Subcommittee of the UNOS Thoracic Organ Committee. The United Network for Organ Sharing manages the national organ transplant waiting list. Our subcommittee devised the current lung allocation system, which took effect in 2005. The old system allocated lungs based on waiting time and geography; the new policy instituted a complicated but much more effective system that allocates lungs to waiting patients based on a Lung Allocation Score. The score is calculated from a combination of clinical data, such as lung function tests, diagnosis, age and other factors that predict risk of dying on the waiting list without a transplant, and risk of dying within a year if a transplant is performed.
The group wanted a system that could adapt to changes in clinical practice and to changes in characteristics of populations of lung transplant candidates. It was based on ethical principles that included equity (fairness and impartiality), creating clinical good for patients, and making the best use of a scarce resource.
The allocation system was first designed using data from adult patients (18 years and older). Analysis of deaths on the waiting list and after transplant identified some factors that predicted these mortality risks, and allowed allocation based on a combination of those risk factors. The intent was to devise a system that reduced deaths on the waiting list while trying to avoid futile transplants in patients with a high risk of death if they had a lung transplant, because they were so ill.
We then analyzed data to see how we could incorporate children into the system. This was challenging because there were so few children listed for lung transplant. We looked at the diagnoses of children listed and found that beyond age 11, most children on the transplant list had diagnoses that were similar to young adults — predominantly cystic fibrosis, some forms of pulmonary fibrosis, and pulmonary hypertension. However, under age 12, the pattern of lung diseases was more unusual, with little data on risk of dying on the list, and very little data on post-transplant death risk because so few lung transplants are performed.
Why? Because there are few children this age listed for lung transplants, and even fewer donors this small. For lung recipients, size is important. Transplanted lungs must fit into the chest of the recipient. A teenage victim of a car accident might have lungs suitable for transplant, but they are too large to fit into the tiny chest of a 10-year-old girl whose growth has been impaired by her disease.
Our subcommittee included all children 12 and older in the analyses, and found that risk factors for death on the waiting list and survival after transplant were the same. So we recommended using the Lung Allocation Score to allocate lungs for everyone 12 and older. At the time, this was very controversial, because we were grouping children and adults together.
The decision to use age 12 as the cutoff for allocation by score was not arbitrary. It was based on the only data we had. For younger children, even though waiting time is not an ideal way to allocate precious and scarce donor organs, the subcommittee had a conference call with the surgeons who perform lung transplants and pediatricians who choose and provide care for the handful of pediatric recipients. They felt that waiting time was as fair as any other way to offer organs to this very diverse group of unfortunate children.
The new system does provide more opportunities for children to be transplanted. Organs from pediatric donors (under age 18) must be offered first to pediatric recipients — to 12-17 year olds based on lung allocation score, and to younger children based on waiting time, before they are offered to adults.
The Lung Allocation Score system has been successful. Deaths on the waiting list have decreased by 40 percent, and the number of lung transplants has increased as surgeons have offered lungs to patients with high scores who were in dire need, rather than to patients who were well enough to continue waiting for the “perfect” donor. Unfortunately, lungs, like many other organs, are still offered locally first, even though wider geographic sharing would reduce wait-list deaths even more.
The sad truth is that there aren’t nearly enough lungs to transplant into all patients with end-stage lung disease at every age. Directed donation isn’t a good answer. Giving a lung to Sarah Murnaghan preferentially denies a transplant to another candidate who also may die waiting.
For some children, two living adults can each donate a lower lobe (half a lung), which function as two lungs in a small recipient. The new lung allocation system made this operation almost obsolete, because if children 12 and older become sicker, their score increases, and they receive lung offers. Living lobe transplants might be an option for Sarah.
There is another solution on the horizon. My lab at the University of North Carolina has pioneered the idea that lungs might be suitable for transplant even if retrieved after death from so-called “non-heart-beating donors.” These are people who have died of cardiac arrest outside the hospital or in the emergency room; circulation has stopped for a period of time (conventional organ donors have been on a ventilator before brain death and organ retrieval).
Our idea is based on the notion that, unlike all other organs that are transplanted, lungs get oxygen from the air inside them, not from blood flow. Use of lungs from these donors requires a huge change in the approach to sudden death by emergency medical services, medical examiners, law enforcement and organ procurement organizations. But because victims of sudden death have not been brain-dead and ventilated for days, their donated lungs may actually be healthier for transplant than lungs from conventional organ donors.
Our UNC group submitted a proposal to the National Institutes of Health to perform this research in North Carolina. We have FDA and UNC Institutional Review Board approval to offer these “non-heart-beating donor” lungs judged suitable for transplant to patients who consent to participate in a clinical trial. But funding has been delayed because of sequestration. We hope to start this project soon; if several transplants are successful, then we will plan a multi-center study to show that the practice is safe. Then there will be many thousands more lungs to transplant into patients who need them.
In the meantime, members of the transplant community are expected to have the wisdom of Solomon in allocating too few organs. What can you do? Sign an organ donation card, and tell your loved ones that you want to be a donor.
Dr. Thomas M. Egan is professor of cardiothoracic surgery at the University of North Carolina at Chapel Hill.