Decline of forced expiratory volume in 1 s after allogeneic hematopoietic cell transplantation is a good indicator for pulmonary damage and is associated with busulfan use.

Reduced pulmonary function is commonly observed after allogeneic hematopoietic stem cell transplantation (HSCT); however, its relationship with the development of noninfectious pulmonary complications (NIPCs) is unclear, and the impact of changes in pulmonary function test (PFT) values on HSCT outcome remains controversial. We conducted a retrospective study including 150 patients to investigate changes in PFTs and impact on clinical outcome. PFT data at around 1 year after HSCT were available in 84 patients, and showed a significant time-dependent decline in percentage predicted forced expiratory volume in 1 s and other parameters. We focused on %FEV1, calculated decline of %FEV1 from pretransplant to around 1 year after HSCT (Δ%FEV1), and divided patients into good-Δ%FEV1 or poor-Δ%FEV1 groups, using a cut-off point of 20% decline of Δ%FEV1. In the poor-Δ%FEV1 group, half of the patients developed NIPCs. In the good-Δ%FEV1 group, PFT values were maintained, whereas those of the poor-Δ%FEV1 group declined significantly. Multivariate analysis showed that busulfan use was a risk factor for %FEV1 decline, and poor-Δ%FEV1 was a risk factor for overall survival. These data indicate that decline of %FEV1 may be a useful indicator of pulmonary damage after HSCT, and is strongly associated with busulfan use.