Prognosis and Risks for Probable Chronic Lung Allograft Dysfunction: A Prospective Multicenter Study

Rationale: Chronic lung allograft dysfunction (CLAD) hinders lung transplant success. A 2019 consensus refined CLAD diagnosis, introducing probable or definite CLAD based on persistence of lung function decline. Outcomes and risks for probable CLAD remain uncertain. Objectives: We sought to determine the prognosis and clinical risks for probable CLAD in a prospective multicenter cohort. Methods: Clinical Trials in Organ Transplantation-20 included 745 CLAD-eligible adult lung recipients at five centers and applied rigorous methods to prospectively adjudicate probable CLAD. The impact of probable CLAD on graft loss was determined using a Cox model that considered CLAD as a time-dependent covariate. Regularized Cox modeling with least absolute shrinkage and selection operator (LASSO) penalty was used to evaluate donor or recipient characteristics and the occurrence and timing of posttransplant events as probable CLAD risks. Similar analyses were performed for definite CLAD. Measurements and Main Results: Probable CLAD occurred in 29.7% of patients at 3 years posttransplant and conferred a marked increase in risk for graft loss (unadjusted hazard ratio = 4.38, P < 0.001). Most patients (80%) with probable CLAD progressed to definite CLAD. Cytomegalovirus infection and, specifically, late presence (>90 d posttransplant) of donor-specific alloantibodies, acute rejection, acute lung injury, or organizing pneumonia contributed the greatest independent information about probable CLAD risk. Definite CLAD risks were similar. Conclusions: Probable CLAD identifies patients at high risk for graft loss, supporting prospective identification of this condition for early initiation of CLAD-directed interventions. More effective strategies to prevent posttransplant cytomegalovirus, inhibit allospecific immunity, and reduce tissue injury are needed to reduce probable CLAD and improve lung recipient survival. Clinical trial registered with www.clinicaltrials.gov (NCT02631720).