The new lung allocation system and its impact on waitlist characteristics and post-transplant outcomes

Historically, waiting time was the primary determinant of lung organ allocation in the United States. Under this system, waiting time grew progressively longer as the annual number of transplants reached a plateau, and every year, a considerable number of candidates died while waiting. In 2005, the lung allocation system changed; under the new system, priority for transplantation is determined by medical urgency and expected outcome. The lung allocation score is based on survival models that estimate waitlist and post-transplant survival, and reflects the net transplant benefit. Early evaluations of the new system indicate that waiting time has decreased, the total number of transplants has increased, waitlist mortality may be decreasing, and survival after transplantation remains unchanged. Over time, refinements in the lung allocation score will likely reduce waitlist mortality further and maintain or perhaps improve survival after transplantation.