Chest computed tomography scores are predictive of survival in patients with cystic fibrosis awaiting lung transplantation

Rationale: Up to a third of cystic fibrosis (CF) patients awaiting lung transplantation (LTX) die while waiting. Inclusion of computed tomography (CT) scores may improve survival prediction models such as the lung allocation score (LAS). Objectives: This study investigated the association between CT and survival in CF patients screened for LTX. Methods: Clinical data and chest CTs of 411 CF patients screened for LTX between 1990 and 2005 were collected from 17 centers. CTs were scored with the Severe Advanced Lung Disease (SALD) 4-category scoring system, including the components "infection/inflammation" (INF), air trapping/hypoperfusion (AT), normal/hyperperfusion (NOR) and bulla/cysts (BUL). The volume of each component was computed using semi-automated software. Survival analysis included Kaplan-Meier curves, and Cox-regression models. Measurements and main results: 366 (186 males) out of 411 patients entered the waiting list (median age 23, range 5-58 years). Subsequently, 67/366(18%) died while waiting, 263/366(72%) underwent LTX, and 36/366(10%) were awaiting LTX at the census date. INF and LAS were significantly associated with waiting list mortality in univariate analyses. The multivariate Cox model including INF and LAS grouped in tertiles and comparing tertiles 2 and 3 to tertile 1, showed waiting list mortality hazard ratios of 1.62 (95%CI 0.78-3.36, p=0.19), and 2.65 (1.35-5.20, p=0.005) for INF and 1.42 (0.63-3.24, p=0.40), and 2.32 (1.17-4.60, p=0.016) for LAS, respectively. These results indicated that INF and LAS had significant, independent predictive value for survival. Conclusions: CT score INF correlates with survival, and adds to the predictive value of LAS.