Association between Vitamin D and Risk for Early and Late Post-Transplant Complications.

Vitamin D (VD) deficiency is a well-described phenomenon in pediatric patients undergoing hematopoietic stem cell transplant (HSCT). VD modulates inflammation, and deficiency pre-HSCT and at day +100 has been associated with graft-versus-host disease (GVHD) and poorer survival. However, a paucity of data has specifically described the association between VD status and immune-mediated complications including GVHD and veno-occlusive disease (VOD). Additionally, data to guide recommendations for VD monitoring and supplementation during HSCT are scarce. Our primary objective was to evaluate the association between VD and post-HSCT complications. The key secondary aim was to evaluate the routine use and efficacy of VD monitoring and supplementation practices. To our knowledge, this is the largest study of its kind in the pediatric population. This retrospective study evaluated VD level (VDL) before and 1 year after HSCT, VD supplementation practices, and their association with acute GVHD, VOD, and survival in pediatric patients who received autologous and allogeneic HSCT for both malignant and nonmalignant diseases from January 2013 to April 2018. Of 314 HSCTs, 43% of patients (n = 136) had VDL measured before HSCT; 61% of this cohort had pre-HSCT VD insufficiency (<30 ng/mL). Neither pre-HSCT nor follow-up VDL was associated with the incidence of GVHD or VOD. Supplementation did not result in significantly different post-HSCT VDL.VDL was correlated with overall survival; every 10-ng/mL increase in VDL was associated with a 28% decreased risk of death (P = .01). Current accepted VD supplementation regimens for pediatric HSCT do not achieve sufficient VDL in most patients after HSCT. VD status was associated with all-cause mortality but not with individual comorbidities; prospective studies are required to establish the connection between VD status, inflammatory-mediated HSCT complications, and potential benefit of VD supplementation before and after HSCT. These studies are needed to inform evidence-based guidelines for monitoring and supplementing VD during HSCT.