Lung function after allogeneic hematopoietic stem cell transplantation in children: a longitudinal study in a population-based cohort.

Reduction in pulmonary function (PF) has been reported in up to 85% of pediatric patients during the first year after hematopoietic stem cell transplantation (HSCT). Our understanding of the etiology for this decrease in lung function is, however, sparse. The aim of this study was to describe PF during follow-up in a population-based pediatric HSCT cohort and to investigate factors in the transplantation process associated with PF decline. A retrospective, population-based, single-center study of HSCT patients spanning 2 decades was performed. Longitudinal changes in PF over time and associations to transplantation-related factors were investigated using a mixed linear model. One hundred thirty patients were included in the longitudinal analysis and observed for a median (range) of 3.3 (.2 to 16.8) years, during which 1084 PF tests were performed. Sixty-two percent of the patients experienced a decline in lung function of more than 10% during the first 3 to 9 months after HSCT. The decline in forced expiratory volume in 1 second, forced expiratory volume in 1 second/forced vital capacity and diffusion capacity of the lung for carbon monoxide were strongly associated with acute graft-versus-host disease (GvHD). Other factors associated with PF decline were malignant diagnosis, busulfan-based conditioning, patient and donor age, female donor to male recipient, as well as chronic GvHD. Mild to moderate decline in PF is frequent and appears associated with acute GvHD and other parameters that are risk factors for chronic GvHD in children. This indicates that alloreactivity is central in pathogenesis of the decrease in PF that follows HSCT in children.