Single Lung Transplant Compared with Double Lung Transplant in Older Adults with Interstitial Lung Disease

Abstract

Purpose Double lung transplant (DLT) is associated with improved long term survival compared with single lung transplant (SLT) in interstitial lung disease (ILD). Recent studies have suggested that this benefit exists for persons above age 65. However, these studies have been limited by non-proportional hazards methodology because the hazard ratios change over time. We postulated that the benefit of double lung transplant would diminish with recipient age using restricted mean survival time analysis (RMST). Methods Using the United Network for Organ Sharing registry, we conducted a retrospective cohort study of 7737 patients with ILD who underwent lung transplant in the U.S. from May 2005 - June 2016. Post-transplant survival was compared using RMST at 5 years post-transplant with a multivariable flexible parametric survival model adjusting for donor and recipient factors. The RMST is a measure of the average survival to a specific time point. Results For all ILD patients, the RMST at 5 years post lung transplant was 3.69 years (95% CI: 3.61-3.77) with DLT compared with 3.42 years (95%CI: 3.33-3.52) with SLT. The benefit was greatest for ILD recipients 60 years or younger, with a RMST of 3.83 (95% CI: 3.75-3.91) with DLT vs. 3.43 (95%CI: 3.24-3.62) with SLT. Above age 60, the benefit of DLT diminished and the RMST for age 60-65, was 3.65 (95% CI: 3.51-3.81) vs. 3.42 (95% CI: 3.26-3.60) for DLT and SLT, respectively. For ages 65-70, survival was nearly equivalent with a RMST of 3.48 (95% CI: 3.25-3.65) vs. 3.36 (95%CI: 3.21-3.51), for DLT and SLT, respectively. Above age 70, there is a trend towards improved survival with SLT, RMST of 2.97 (95% CI: 2.45-3.60) vs. 3.14 years (95% CI: 2.94-3.35) for DLT and SLT, respectively. Conclusion SLT is associated with similar survival to DLT for ILD recipients above age 65. Given the relative organ shortage, the transplant community should consider preferential single lung transplant for the majority of older ILD transplant candidates. Double lung transplant (DLT) is associated with improved long term survival compared with single lung transplant (SLT) in interstitial lung disease (ILD). Recent studies have suggested that this benefit exists for persons above age 65. However, these studies have been limited by non-proportional hazards methodology because the hazard ratios change over time. We postulated that the benefit of double lung transplant would diminish with recipient age using restricted mean survival time analysis (RMST). Using the United Network for Organ Sharing registry, we conducted a retrospective cohort study of 7737 patients with ILD who underwent lung transplant in the U.S. from May 2005 - June 2016. Post-transplant survival was compared using RMST at 5 years post-transplant with a multivariable flexible parametric survival model adjusting for donor and recipient factors. The RMST is a measure of the average survival to a specific time point. For all ILD patients, the RMST at 5 years post lung transplant was 3.69 years (95% CI: 3.61-3.77) with DLT compared with 3.42 years (95%CI: 3.33-3.52) with SLT. The benefit was greatest for ILD recipients 60 years or younger, with a RMST of 3.83 (95% CI: 3.75-3.91) with DLT vs. 3.43 (95%CI: 3.24-3.62) with SLT. Above age 60, the benefit of DLT diminished and the RMST for age 60-65, was 3.65 (95% CI: 3.51-3.81) vs. 3.42 (95% CI: 3.26-3.60) for DLT and SLT, respectively. For ages 65-70, survival was nearly equivalent with a RMST of 3.48 (95% CI: 3.25-3.65) vs. 3.36 (95%CI: 3.21-3.51), for DLT and SLT, respectively. Above age 70, there is a trend towards improved survival with SLT, RMST of 2.97 (95% CI: 2.45-3.60) vs. 3.14 years (95% CI: 2.94-3.35) for DLT and SLT, respectively. SLT is associated with similar survival to DLT for ILD recipients above age 65. Given the relative organ shortage, the transplant community should consider preferential single lung transplant for the majority of older ILD transplant candidates.