The association of lung function changes with outcomes in children with bronchiolitis obliterans syndrome after hematopoietic stem cell transplantation.

BACKGROUND Bronchiolitis obliterans syndrome (BOS) is a life-threatening respiratory complication of allogeneic hematopoietic stem cell transplantation (HSCT). Although pulmonary function testing is crucial for monitoring BOS, little information exists on the association of these test results with outcomes in children with BOS. OBJECTIVES The purpose of this study was to determine the correlation between changes in lung function after BOS diagnosis and long-term outcomes. METHODS A total of 428 children underwent allogeneic HSCT from January 2006 to December 2017 at Asan Medical Center. Twenty-three (5.4%) were diagnosed with BOS after allogeneic HSCT, and their clinical data were reviewed. Twenty-one subjects underwent regular pulmonary function testing for 24 months after BOS diagnosis. RESULTS Among the 21 children with BOS, 8 died, 5 underwent lung transplantation (TPL), and 15 required oxygen (O2 ) therapy. The FEV1 % predicted (pred), FVC% pred, and FEF25%-75% pred were 37.8 ± 12.7% (mean ± SD), 62.2 ± 16.2%, and 16.4 ± 9.6%, respectively, at the time of BOS diagnosis. Changes in the FEV1 % pred were greater in the death and lung TPL groups (-24.8 ± 22.3%) than in the survival without lung TPL group (5.7 ± 21.8%) and greater in the O2 therapy (-19.4 ± 23.4%) group than in the group without O2 therapy (14.2 ± 20.0%) during the first 3 months after BOS diagnosis. CONCLUSION The change in FEV1 during the first 3 months after BOS diagnosis correlated with outcomes including survival, lung TPL, and O2 therapy. These results suggest that more active intervention in the first 3 months after BOS diagnosis may be needed to improve prognosis.