Clinical profile and risk factors of low percent vital capacity after allogeneic hematopoietic stem cell transplantation.

Abstract

Late-onset noninfectious pulmonary complications are potentially fatal after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Pulmonary function tests (PFTs) are widely used during post-transplant follow-up. While obstructive lung disease associated with chronic graft-versus-host disease (cGVHD) has been well studied, evidence regarding restrictive lung disease, including low percent vital capacity (LPVC), remains limited. This study aimed to investigate the impact of post-HSCT LPVC and to identify the risk factors and the timing of its onset. LPVC was defined as percent vital capacity (%VC) <80% on two consecutive PFTs. Among 492 patients undergoing allo-HSCT between 2006 and 2020, 102 patients with normal pretransplant pulmonary function and at least two post-transplant PFTs were retrospectively analyzed, excluding those with respiratory symptoms at the initiation of post-transplant follow-up. LPVC developed in 21 patients, with a 5-year cumulative incidence of 19.9% (95% confidence interval, 13.3-29.1%). Risk factors for LPVC included moderate/severe cGVHD, lower body mass index (BMI), lower pretransplant %VC, HLA-matched unrelated peripheral blood stem cell transplantation, and umbilical cord blood transplantation. LPVC diagnosis was associated with poorer overall survival (OS), higher nonrelapse mortality and increased incidence of infectious pneumonia. In patients with LPVC, further risk factors for OS included a decline in %VC to ≤70% from the value at LPVC diagnosis, lower BMI at LPVC detection and higher refined disease risk index. LPVC after allo-HSCT is associated with unfavorable prognosis. Careful monitoring of %VC decline after LPVC diagnosis is important for prognostic assessment.