Single- vs Double-Lung Transplantation in Patients With Chronic Obstructive Pulmonary Disease and Idiopathic Pulmonary Fibrosis Since the Implementation of Lung Allocation Based on Medical Need

IMPORTANCE Outcomes of single-and double-lung transplantation have not been rigorously assessed since the allocation of donor lungs according to medical need as quantified by the Lung Allocation Score, which began in 2005. OBJECTIVE To compare outcomes in single-and double-lung transplant recipients since the Lung Allocation Score was implemented. DESIGN, SETTING, AND PARTICIPANTS In this exploratory analysis, adults with idiopathic pulmonary fibrosis (IPF) or chronic obstructive pulmonary disease (COPD) who underwent lung transplantation in the United States between May 4, 2005, and December 31, 2012, were identified in the United Network for Organ Sharing thoracic registry, with follow-up to December 31, 2012. Posttransplantation graft survival was assessed with Kaplan-Meier analysis. Propensity scores were used to control for treatment selection bias. A multivariable flexible parametric prognostic model was used to characterize the time-varying hazard associated with single-vs double-lung transplantation. EXPOSURE Single-or double-lung transplantation. MAIN OUTCOMES AND MEASURES Composite of posttransplant death and graft failure (retransplantation). RESULTS Patients with IPF (n = 4134, of whom 2010 underwent single-lung and 2124 underwent double-lung transplantation) or COPD (n = 3174, of whom 1299 underwent single-lung and 1875 underwent double-lung transplantation) were identified as having undergone lung transplantation since May 2005. Median follow-up was 23.5 months. Of the patients with IPF, 1380 (33.4%) died and 115 (2.8%) underwent retransplantation; of the patients with COPD, 1138 (34.0%) died and 59 (1.9%) underwent retransplantation. After confounders were controlled for with propensity score analysis, double-lung transplants were associated with better graft survival in patients with IPF (adjusted median survival, 65.2 months [interquartile range {IQR}, 21.4-91.3 months] vs 50.4 months [IQR, 17.0-87.5 months]; P < .001) but not in patients with COPD (adjusted median survival, 67.7 months [IQR, 25.2-89.6 months] vs 64.0 months [IQR, 25.2-88.7 months]; P = .23). The interaction between diagnosis type (COPD or IPF) and graft failure was significant (P = .049). Double-lung transplants had a time-varying association with graft survival; a decreased instantaneous late hazard for death or graft failure among patients with IPF was noted at 1 year and persisted at 5 years postoperatively (instantaneous hazard at 5 years, hazard ratio, 0.67 [95% CI, 0.52-0.84] in patients with IPF and 0.89 [95% CI, 0.71-1.13] in patients with COPD). CONCLUSIONS AND RELEVANCE In an exploratory analysis of registry data since implementation of a medical need-based lung allocation system, double-lung transplantation was associated with better graft survival than single-lung transplantation in patients with IPF. In patients with COPD, there was no survival difference between single-and double-lung transplant recipients at 5 years.