Clinical impact of airflow obstruction after allogeneic hematopoietic stem cell transplantation

Criteria for airflow obstruction (AFO) at one year after allogeneic hematopoietic stem cell transplantation (allo-HSCT) in pulmonary function tests (PFTs) are more stringent than the bronchiolitis obliterans syndrome (BOS) criteria of the National Institutes of Health. This single-center, retrospective cohort study evaluated the clinical impact of the AFO criteria at any time after transplantation. In 132 patients who underwent allo-HSCT from 2006 to 2016, the 2-year cumulative incidence of AFO was 35.0%, and the median time to diagnosis of AFO was 101 days after transplantation (range 35-716 days). Overall chronic graft-versus-host disease (cGVHD) incidence was significantly higher in patients with AFO than in those without AFO (80.4% vs. 47.7%, P < 0.01); notably, 37.0% of patients with AFO developed cGVHD after AFO diagnosis. AFO patients developed BOS with a 5-year cumulative incidence of 49.1% after AFO onset. The 5-year cumulative incidence of non-relapse mortality in the AFO group was higher than that in the non-AFO group (24.7% vs. 7.1%, P < 0.01). These results suggest that closely monitoring PFTs within two years after allo-HSCT, regardless of cGVHD status, is important for early detection of AFO and prevention of progression to BOS. (192words).