The clinical significance of baseline lung allograft dysfunction in single and bilateral lung transplant recipients

Baseline lung allograft dysfunction (BLAD), defined as failure to achieve normal peak lung function after transplant, is associated with decreased survival in bilateral orthotopic lung transplant recipients. Limited data exist regarding the BLAD outcome in single orthotopic lung transplant (SOLT). We hypothesized that post-transplant survival in SOLT recipients with BLAD would differ according to native lung disease physiology.

In our single-center retrospective cohort study, we reviewed the pulmonary function test data of 1,086 first lung transplant recipients between January 2000 and January 2020. We performed a landmark analysis examining survival landmarked at 1-year post-transplant. We used Cox proportional hazards regression to assess the baseline forced expiratory volume in one second (FEV1) percent predicted in the first year post-transplant with survival after 1 year. In SOLT patients, analysis was stratified by interstitial lung disease (ILD) and obstructive lung disease (OLD).

Our final cohort included 797 patients, 446 BOLT and 351 SOLT. Among SOLT patients, 263 had native ILD and 88 had native OLD. We confirmed that BLAD is associated with decreased survival in BOLT driven by BLAD grades 3 & 4. In recipients of SOLT, we found similar decreased survival with BLAD among those with native ILD, driven by grades 2, 3, & 4. However, BLAD was not associated with decreased survival in SOLT patients with native OLD, except at grade 4 (FEV1<35%).

In SOLT recipients with native ILD, BLAD was associated with worse post-transplant survival, particularly at higher BLAD grades, similar to patterns observed in BOLT recipients. In contrast, among SOLT recipients with native OLD, variable native lung hyperinflation and mechanical effects will affect post-transplant baseline lung function with less clear implications for graft function and survival.