Impact of U.S. Lung Allocation Score on Survival After Lung Transplantation

Abstract

The Lung Allocation Score (LAS) dramatically changed organ allocation in lung transplantation. The impact of this change on patient outcomes is unknown. The purpose of the study was to examine early mortality after lung transplantation under the LAS system. All patients undergoing first-time lung transplantation during the period from May 1, 2005 through April 30, 2008 were included in the study. The cohort was divided into quintiles by LAS. A high-risk group (LAS >46) was comprised of the highest quintile, Quintile 5, and a low-risk group (LAS < or =46) included the lower quintiles, Quintiles 1 through 4. A time-to-event analysis was performed for risk of death after transplantation using Kaplan-Meier survival and Cox proportional hazards models. There were 4,346 patients who underwent lung transplantation during the study period. Patients in the high-risk group (LAS >46) were more likely to have idiopathic pulmonary fibrosis (IPF; 52.9% vs 23.8%, p < 0.001) and diabetes (25.8% vs 16.8%, p < 0.001) and to require mechanical ventilatory support (15.4% vs 2.2%, p < 0.001) at the time of transplant as compared with patients in the low-risk group. One-year survival using the Kaplan-Meier product limit estimator was significantly worse in the high-risk group (75% vs 83%, p < 0.001 by log-rank test). Patients in the high-risk group were also found to have increased risk of death (hazard ratio 1.46, 95% confidence interval 1.24 to 1.73) compared with the low-risk group. Overall 1-year survival under the new LAS system appears to be similar to that in historic reports. However, risk of death was significantly increased among patients with LAS >46.