Impact of Forced Expiratory Volume in 1 Second (FEV1) and 6-Minute Walking Distance at 3, 6, and 12 Months and Annually on Survival and Occurrence of Bronchiolitis Obliterans Syndrome (BOS) After Lung Transplantation

BACKGROUND Development of bronchiolitis obliterans syndrome (BOS) is a great limitation for patient survival in lung transplantation (LTx). A curative treatment for BOS is still missing, and in terminal stages re-transplantation (Re-LTx) is the only salvation. It is possible to slow the progress of BOS if it is detected at an early stage. This might be possible by assessing pulmonary function pattern. MATERIAL AND METHODS Between 1990 and 2014, 278 patients underwent LTx at Skåne University Hospital, Sweden. Pulmonary function was followed using spirometry (FEV1) and 6-minute walking test (6MWT) measured at 3, 6, and 12 months and annually. The endpoint used was freedom from BOS (BOS grade ≤1), BOS (BOS grade ≥2), and death or Re-LTx. RESULTS Double-lung transplantation (DLTx) showed a hazard ratio (HR) of 0.514 (p=0.001) versus recipients who underwent single-lung transplantation (SLTx). Regarding freedom from BOS, FEV1 showed an HR of 0.597 and 6MWT an HR of 0.982 (p<0.001). Regarding combined endpoint BOS ≥2 and Re-LTx, FEV1 showed an HR of 0.618 and 6MWT an HR of 0.972 (p<0.001). CONCLUSIONS Recipients with higher FEV1 or 6MWT values had better chances of survival. Recipients with DLTx had a significant survival benefit and a protective effect against development of BOS. As the distance that the patient can walk in 6 minutes increases, risk for death or Re-LTx is significantly lower, as is incidence of developing BOS grade ≥2. Understanding changes within pulmonary function are probably key to understanding patient prognosis.