Bronchodilator Response: Utility and implications in patients undergoing hematopoietic stem cell transplantation

Bronchodilator response (BDR) assessment is routinely included in pulmonary evaluation before hematopoietic cell transplantation (HCT), but its prognostic significance remains uncertain. Recent European Respiratory Society/American Thoracic Society (ERS/ATS) criteria changes complicate interpretation.

To examine associations between BDR and clinical outcomes in HCT recipients and compare prognostic utility of traditional versus revised BDR criteria.

In this single-center study of 1,255 adult allogeneic HCT recipients (2005-2021), we assessed BDR using both 2005 criteria (≥12 % and ≥200 mL increase in FEV₁/FVC) and 2022 criteria (>10 % of predicted increase). Primary outcomes included bronchiolitis obliterans syndrome (BOS) development, 120-day ICU admission, and survival.

Among patients (58 % male, mean age 51.3 ± 13.6 years), positive BDR frequency was low (11.5 % by 2005 criteria, 14.2 % by 2022 criteria), with high concordance (>94 %). BDR did not predict BOS development, with similar pre-transplant FEV₁ responses between patients who later developed BOS and those who did not (5.0 % vs. 4.9 %, p = 0.841). Unadjusted analyses showed pre-transplant BDR positivity using 2005 criteria was associated with increased mortality (HR = 1.45, p = 0.006) and ICU admission (HR = 1.65, p = 0.005), but these associations did not persist after adjusting for baseline FEV₁ (aHR = 1.17, p = 0.275; aHR = 1.09, p = 0.648).

BDR testing provides minimal additional prognostic information beyond baseline lung function assessment in HCT recipients and does not predict BOS development. Our findings support that BOS represents a fibroproliferative process distinct from disorders characterized by airway hyperresponsiveness, suggesting bronchodilator testing could be eliminated from standard HCT protocols without compromising risk assessment.