LAS VEGAS – The 2005 revision of the lung allocation system for U.S. lung transplants succeeded, resulting in fewer patients dying while on the lung waiting list, Dr. Robert M. Kotloff said at the annual meeting of the National Association for Medical Direction of Respiratory Care.
Reduced deaths in wait-listed patients "was the major goal" of the revision, "so the LAS [lung allocation system] worked," said Dr. Kotloff, professor of medicine and chief of the section of advanced lung disease and lung transplantation at the University of Pennsylvania in Philadelphia.
Dr. Robert M. Kotloff
The new LAS also triggered other changes in the pattern of U.S. lung transplantations during the subsequent 5 years, some of which took several years to become apparent.
The revised system for allocation of donor lungs shifted the weight of the different pulmonary diseases that lead to lung transplantation, reducing the priority of chronic obstructive pulmonary disease (COPD) and boosting the importance of idiopathic pulmonary fibrosis (IPF). As recently as a decade ago, 45% of U.S. lung transplantations were done in patients with COPD and 20% in those with IPF. Although the gap between the two had narrowed considerably by 2005, that year COPD still remained the leading indication. But by 2007, IPF inched ahead of COPD, and today IPF is the leading reason why U.S. patients receive a lung transplant, Dr. Kotloff said.
"IPF is a no-brainer for listing," with a median survival of 3-4 years, and with half of IPF deaths occurring after a sudden patient decline, he said. Although some patients have an indolent form of IPF, "what’s unsettling is that half of IPF deaths are sudden and unpredictable, occurring in patients who recently had stable or mild disease. We have all had IPF patients who were told they weren’t sick enough to list and to return in 6 months – who then show up in the ICU on a ventilator, a missed opportunity" for transplantation. Because of experiences like these, IPF patients now undergo a thorough evaluation for transplantation so that if they suddenly wind up in the ICU, it’s easier to get them a transplant quickly.
Patients who receive a lung transplant have a median 5-year survival rate of 50%, which means that patients with a disease that has a similar or better prognosis are not good candidates. The poorer average survival rate of IPF patients helps explain why they are good transplant candidates.
The U.S. Department of Health and Human Services mandated a 2005 revision of the allocation systems for all organs based on medical urgency rather than time on the waiting list, a system biased against patients with more aggressive disease such as IPF. The LAS scoring formula put in place by the Organ Procurement and Transplantation Network took into account both the urgency of a patient’s need for a lung transplant and the patient’s likelihood of survival following transplantation (Chest 2007;132:1954-61). Two patient features carry the most weight in the formula: the patient’s underlying disease, and whether the patient requires mechanical ventilation and how much oxygen he or she needs. Today, about the only way for a patient to have a really high LAS score of 80 or greater is to be on a ventilator with high-flow oxygen.
The 2005 LAS revision led to a dramatic shortening of the U.S. waiting list for lungs – from more than 2,000 patients before 2005 to roughly 1,000 patients today – largely because it deemphasized time on the list and made "time banking" unnecessary. Time banking had been a practice by which potential lung transplant candidates without an immediate need got listed in case they needed a transplant in the future. If they did eventually need a transplant, they had accumulated time on the list, which boosted their chances of getting the transplant more quickly. If they eventually got a call for a transplant but still did not immediately need it, they could withdraw from accepting that organ but still retain their relatively high priority on the list, Dr. Kotloff explained.
With the new allocation formula, patients with no immediate need and an uncertain future need for a transplant, such as many COPD patients, are simply kept off the list until their transplant need becomes clear. The downside to the current system is that many patients with potentially severe and unstable lung disease, such as many IPF patients, move from referral to listing to transplantation in just a few weeks – so rapidly that they do not have time to receive adequate counseling about the consequences and possible drawbacks of lung transplantation, Dr. Kotloff said.