Survival Benefit of Lung Transplantation in the Modern Era of Lung Allocation

Abstract

Rationale: Lung transplantation is an accepted and increasingly employed treatment for advanced lung diseases, but the anticipated survival benefit of lung transplantation is poorly understood.

Objectives: To determine whether and for which patients lung transplantation confers a survival benefit in the modern era of U.S. lung allocation.

Methods: Data on 13,040 adults listed for lung transplantation between May 2005 and September 2011 were obtained from the United Network for Organ Sharing. A structural nested accelerated failure time model was used to model the survival benefit of lung transplantation over time. The effects of patient, donor, and transplant center characteristics on the relative survival benefit of transplantation were examined.

Measurements and main results: Overall, 73.8% of transplant recipients were predicted to achieve a 2-year survival benefit with lung transplantation. The survival benefit of transplantation varied by native disease group (P = 0.062), with 2-year expected benefit in 39.2 and 98.9% of transplants occurring in those with obstructive lung disease and cystic fibrosis, respectively, and by lung allocation score at the time of transplantation (P < 0.001), with net 2-year benefit in only 6.8% of transplants occurring for lung allocation score less than 32.5 and in 99.9% of transplants for lung allocation score exceeding 40.

Conclusions: A majority of adults undergoing transplantation experience a survival benefit, with the greatest potential benefit in those with higher lung allocation scores or restrictive native lung disease or cystic fibrosis. These results provide novel information to assess the expected benefit of lung transplantation at an individual level and to enhance lung allocation policy.

Keywords: lung allocation score; lung transplantation; structural nested accelerated failure time model; survival benefit.

Figure 1.

Relative survival benefit, varying recipient and donor factors. Estimated relative survival benefit at 2 years by changing a single recipient and donor factor from the reference level of the recipient and donor factors (bilateral transplant; restrictive native lung disease; LAS-T = 38.7; recipient age, 58 yr; donor age, <55 yr; donor smoking history, <20 pack-years; height difference [i.e., recipient height − donor height], <0 cm). For example, a 2-year relative survival benefit of 1.5 indicates that a person receiving a transplant with the given recipient and donor characteristics would have the same probability of dying within 2 years posttransplantation as in 2/1.5 = 1.33 years if never transplanted. A relative survival benefit greater than 1 indicates that for those recipient and donor characteristics transplantation confers a 2-year survival benefit relative to remaining untransplanted on the waiting list. Diff = difference; LAS-T = lung allocation score at transplantation; LTx = lung transplantation.

Figure 2.

Cumulative incidence of death posttransplantation compared with the waiting list. Shown is the estimated cumulative incidence of death after transplantation (solid blue line) and had the candidates never been transplanted (red dashed line) among the 9,091 study participants who were transplanted. LAS = lung allocation score; Tx = transplantation.