PURPOSE: Pre-lung transplant mechanical ventilation (MV) is a predictor of reduced post-transplant survival and thus is a relative contraindication to transplantation. In 2005, lung allocation transitioned to a priority-based system based on Lung Allocation Score (LAS). Under the LAS, patients supported by MV receive higher transplant priority. We examined the effect of MV on post-transplant survival in the LAS era.
METHODS: Using the Organ Procurement and Transplantation Network Registry, we identified all patients in the US age ≥18 years undergoing lung transplantation between 5/4/05-11/27/09. Post-transplantation survival time was the primary study outcome. To adjust for illness severity, we generated propensity scores predicting MV for each transplant recipient. Allen-Cady backward stepwise regression (p<0.2) was used to select covariates for use in the propensity score. Variables included in the final propensity score model were LAS, diagnosis, FEV1, age, transplant year, and arterial pCO2. Based on propensity scores, a nearest-neighbor matching algorithm identified a non-ventilated match for each ventilated patient. Post-transplant survival was assessed with Kaplan-Meier methods. Log rank was used to test survivor function equality.
RESULTS: Of 6,532 transplantations performed during the study period, 356 (5.5%) patients received pre-transplant MV support. After matching, patients receiving and not receiving pre-transplant MV support were balanced for age, gender, FEV1, FVC, BMI, creatinine, and LAS (p≥0.2). Patients with MV support had reduced post-transplant survival at: 6 months (76%), 1 year (68%), 2 years (58%), and 3 years (52%) compared to non-MV supported patients (87%, 79%, 68%, and 60%, respectively; p≤0.005).
CONCLUSION: In the LAS era, pre-transplant MV is associated with reduced post-lung transplant survival. Based on propensity score adjustment, MV is not merely a marker of disease severity but may be associated with other factors (e.g., infection and deconditioning) causally linked to reduced post-transplant survival.
CLINICAL IMPLICATIONS: For patients supported by MV, careful evaluation of the risks and benefits of lung transplantation are warranted; future studies should identify specific predictors of reduced survival for patients supported by MV prior to transplantation.
DISCLOSURE: Jonathan Singer, No Financial Disclosure Information; No Product/Research Disclosure Information