One-year lung function change and variability post allogeneic hematopoietic stem cell transplantation

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a well-established treatment for various haematologic and oncologic disorders, yet its clinical success is frequently compromised by complications such as pulmonary graft-versus-host disease (GvHD). Spirometry is the gold standard for monitoring and diagnosis, but it is insensitive to small airway changes. Oscillometry may complement spirometry as a way of detecting change in small airway function. This study assessed the longitudinal change and variability in spirometry and oscillometry following allo-HSCT and predictors of this change.

Longitudinal spirometry and oscillometry were retrospectively obtained from all patients (n = 374) who underwent allo-HSCT at Royal North Shore Hospital in Sydney, Australia, between January 2015 and December 2023.

Baseline post allo-HSCT assessments showed significantly lower FEV₁ and FVC in the allo-HSCT group compared to controls. Over the follow-up period, oscillometric indices displayed significant worsening of Rrs₅ and Xrs₅, whereas FEV₁ did not significantly change. Severe cGvHD was associated with a modest decline in FEV₁/FVC and Xrs₅ trajectory. Notably, a subset of patients demonstrated discordant changes between spirometry and oscillometry, suggesting that oscillometry may capture early small airway dysfunction not evident on traditional spirometric measures.

These findings underscore the potential of oscillometry as a complementary tool in the routine monitoring of lung function post-allo-HSCT. By detecting subtle changes in small airway mechanics, oscillometry could facilitate earlier identification and intervention in patients at risk for developing pulmonary cGvHD, thereby improving long-term clinical outcomes.