Lung size mismatch and survival after single and bilateral lung transplantation

Abstract

Background: A higher predicted total lung capacity (pTLC)-ratio (=pTLC donor/pTLC recipient), suggestive of oversized allografts, is associated with improved survival after lung transplantation. It is unknown whether the pTLC-ratio has a different association with survival in bilateral (BLT) versus single lung transplantation (SLT).

Methods: The pTLC-ratio was calculated for all adult patients in the United Network of Organ Sharing lung transplant (LTx) registry who underwent first-time LTx in the post lung allocation score era, between May 2005 and April 2010. The LTx recipients were stratified according to procedure (BLT vs SLT). Risk of death at 1 year after LTx was analyzed using Kaplan-Meier survival and Cox proportional hazards models.

Results: In the 4,520 BLT patients, each 0.1 increase in pTLC-ratio conferred a 7% decrease in the hazard for death at 1 year (p < 0.001) in univariate analysis. This association remained significant after controlling for diagnosis, comorbidities, acuity, donor, and transplant factors (hazard ratio [HR] 0.93, 95% confidence interval [CI] 0.88 to 0.98, p = 0.01). Additional adjustment by a propensity score to account for biases to oversizing showed similar results (HR 0.94, 95% CI 0.90 to 0.99, p = 0.018). In the 2,477 SLT patients, each 0.1 increase in pTLC-ratio conveyed a 6% decrease in the hazard for death at 1 year (p = 0.002) in univariate analysis, which did not persist in the multivariate model (HR 1.00, p = 0.8).

Conclusions: A higher pTLC-ratio, suggestive of an oversized allograft, is associated with improved survival after lung transplantation. This association is primarily evident in BLT patients.

Keywords: 12.