Abstract
RATIONALE: Early diagnosis of bronchiolitis obliterans syndrome (BOS) is critical in understanding pathogenesis and devising therapeutic trials. Although potential-BOS stage (BOS 0-p), encompassing early changes in FEV(1) and forced expiratory flow, midexpiratory phase (FEF(25-75%)), has been proposed, there is a paucity of data validating its utility in single-lung transplantation. OBJECTIVE: The aim of this study was to define the predictive ability of BOS 0-p in single-lung transplantation. METHODS: We retrospectively analyzed spirometric data for 197 single-lung recipients. Sensitivity, specificity, and positive predictive value of BOS 0-p were examined over time using Kaplan-Meier methodology. RESULTS: BOS 0-p FEV(1) was associated with higher sensitivity, specificity, and positive predictive value than the FEF(25-75%) criterion over different time periods investigated. The probability of testing positive for BOS 0-p FEV(1) in patients with BOS (sensitivity) was 71% at 2 years before the onset of BOS. The probability of being free from development of BOS 0-p FEV(1) in patients free of BOS at follow-up (specificity) was 93% within the last year. Of patients who met the BOS 0-p FEV(1) criterion, 81% developed BOS or died within 3 years. The specificity and positive predictive value curves for the BOS 0-p FEV(1) were significantly different between patients with underlying restrictive versus obstructive physiology (p = 0.05 and 0.01, respectively). CONCLUSION: The FEV(1) criterion for BOS 0-p provides useful predictive information regarding the risk of development of BOS or death in single-lung recipients. The predictive value of this criterion is higher in patients with underlying restriction and is superior to the FEF(25-75%) criterion.