Revisiting the pathologic finding of diffuse alveolar damage after lung transplantation.

BACKGROUND: Diffuse alveolar damage (DAD) is a non-specific pathologic diagnosis frequently encountered after lung transplantation. We examined the relationship between DAD and different forms of chronic lung allograft dysfunction (CLAD).

METHODS: We reviewed the results of 4,085 transbronchial biopsies obtained from 720 lung transplant recipients. DAD detected in biopsies within 3 months and newly detected DAD after 3 months were defined as early DAD and late new-onset DAD, respectively. Among patients with CLAD (FEV(1) <80% baseline), restrictive allograft syndrome (RAS) was defined by a decline in total lung capacity to <90% baseline and bronchiolitis obliterans syndrome (BOS) as CLAD without restrictive allograft syndrome (RAS). Kaplan-Meier analyses and multivariate proportional hazard models were used.

RESULTS: DAD was observed in 320 of 720 (44.4%) patients at least once; early and late new-onset DAD were observed in 264 of 707 (37.3%) and 87 of 655 (13.3%) patients, respectively. Early DAD was associated with significantly higher 90-day mortality (20 of 264 [7.6%] vs 11 of 443 [2.5%]; p = 0.001). Moreover, among 502 bilateral lung transplant recipients who had sufficient pulmonary function tests to distinguish BOS and RAS, early DAD was associated with earlier BOS onset (hazard ratio [HR] 1.24; confidence interval [CI] 1.04 to 1.47; p = 0.017; median time of BOS onset: 2,902 vs 4,005 days). Conversely, treated as a time-varying covariate, late new-onset DAD was a significant risk factor for RAS in a Cox model (HR 36.8; CI 18.3 to 74.1; p < 0.0001).

CONCLUSIONS: Early DAD is associated with early mortality and BOS, and late new-onset DAD increases the risk of RAS.