Pretransplant Small-airway Dysfunction is Associated with Posttransplant Complications in Adult HSCT Recipients

Pulmonary function testing is routinely performed before hematopoietic stem cell transplantation (HSCT), but conventional parameters may not capture subtle airway abnormalities. This study evaluated the association of pretransplant forced expiratory flow between 25% and 75% of forced vital capacity (FEF_25-75) with post-HSCT complications in adults.

This retrospective single-center cohort included 83 adults who underwent HSCT between 2016 and 2023. Reduced FEF_25-75 was defined as <75% predicted. The primary outcome was a composite of post-HSCT complications. Multivariable logistic regression models were adjusted for age, sex, ever-smoking status, HSCT type, and reduced forced expiratory volume in 1 second (FEV₁). Discrimination was assessed using receiver operating characteristic analysis.

Overall, 32 patients (38.6%) experienced post-HSCT complications. Complications occurred in 50.0% of patients with reduced FEF_25-75 versus 28.9% of those with FEF_25-75 ≥75% predicted (P = 0.049). Reduced FEF_25-75 was independently associated with higher odds of complications [odds ratio (OR): 3.58, 95% confidence interval (CI): 1.28-10.04; P = 0.015]. Reduced FEV₁ showed an inverse association (OR: 0.12, 95% CI: 0.02-0.71; P = 0.019). FEF_25-75 showed poor standalone discrimination (area under the curve: 0.578, 95% CI: 0.450-0.705).

Reduced pretransplant FEF_25-75 was independently associated with post-HSCT complications, but showed poor standalone discrimination. These hypothesis-generating findings suggest that FEF_25-75 may provide information complementary to FEV₁, but they do not support its use as an independent predictive test. Larger prospective studies are required.