ARDS during haematopoietic reconstruction after allogeneic haematopoietic stem cell transplantation (allo-HSCT) in non-child patients: based on the new global definition.

Background: Haematopoietic reconstitution is marked by immunosuppression and pancytopenia, representing the initial high-risk period following allogeneic haematopoietic stem cell transplantation (allo-HSCT). However, little is known about the occurrence of acute respiratory distress syndrome (ARDS) during haematopoietic reconstitution.

Methods: This retrospective cohort study included 1024 patients who underwent allo-HSCT in Suzhou from 2016 to 2019. Clinical data and follow-up information were collected from medical records. ARDS was defined according to the new global definition established in 2023. The primary outcomes were the incidence of ARDS during haematopoietic reconstitution after allo-HSCT and 1 year post-transplantation mortality.

Results: Among the 1024 patients, 58 (5.6%) died within 1 year after HSCT. ARDS during haematopoietic reconstitution occurred in 45 patients (4.4%), of whom 29 were treated with high-flow nasal oxygen only. The median onset of ARDS was 9.0 days post-transplantation. Patients who developed ARDS had a significantly higher risk of 1-year mortality after HSCT (HR 7.99, 95% CI 4.13 to 15.44). Independent risk factors for ARDS during haematopoietic reconstitution included longer intervals between disease onset and transplantation (OR 1.01, 95% CI 1.00 to 1.02), a greater number of previous HSCTs (OR 1.82, 95% CI 1.04 to 3.19), and higher red cell distribution width at admission (OR 1.12, 95% CI 1.02 to 1.22).

Conclusions: According to the new 2023 global definition, ARDS during haematopoietic reconstitution is independently associated with increased 1-year mortality after allo-HSCT. Early identification of ARDS during this period is particularly important, and recognising its risk factors may aid in timely diagnosis and intervention.