Elevated Radiographic Assessment of Lung Edema (RALE) score on day 3 after lung transplantation is associated with poor clinical outcomes.

Abstract

Background: Primary graft dysfunction (PGD) is associated with lung transplant recipient mortality. However, PGD severity based on hypoxemia may overestimate alveolar edema. We tested whether quantification of pulmonary edema using the Radiographic Assessment of Lung Edema score (RALE) is associated with PGD, hospital length of stay (LOS), or death in a retrospective cohort study.

Methods: The cohort included double lung transplant recipients from two Lung Transplant Outcomes Group centers (LTOG, n=253) and Vanderbilt University Medical Center (VUMC, n=252). RALE score (extent and density of opacities) was determined from chest radiographs from post-operative day 3.

Results: Median day 3 RALE was 19 (quartiles 13-26) in LTOG and 16 (12-21) at VUMC. Patients with PGD2 or PGD3 had significantly higher RALE than patients with PGD 0/1. There was no association between PaO₂/FiO₂ and LOS or mortality. In LTOG, a 5-point increase in RALE associated with a 3.3-day increase in LOS (95%CI 1.7-4.7, p<0.001) and a 41% increase in 1-year mortality (HR 1.4, 95%CI 1.2-1.8) (p<0.001), each independent of hypoxemia. At VUMC, a 5-point increase in RALE associated with a 4.5-day increase in LOS (95%CI: 2.6-6.4, p<0.001), independent of hypoxemia, but was not associated with mortality (p=0.54).

Conclusions: In lung transplant recipients, RALE is associated with PGD grade and is a strong predictor of hospital LOS. These associations are independent of hypoxemia, suggesting that radiographic assessment provides prognostic information beyond severity of hypoxemia. Quantification of pulmonary edema using RALE may be useful for identifying lung transplant recipients at high risk of poor clinical outcomes.