Effects of Vitamin D Levels on Outcomes after Allogeneic Hematopoietic Stem Cell Transplantation in Children

Vitamin D deficiency (VDD) has been linked to multiple autoimmune disorders because of its importance in self-tolerance and effect on multiple immune system cells. A few studies have shown that patients with VDD may have increased risk of GvHD, CMV infection and decreased overall survival after HSCT, conversely, a study from Brazil showed no such correlations. To better identify the role of vitamin D in children undergoing HSCT, we present the results of a retrospective multicenter study. Records of patients who underwent allogeneic HSCT from January 1, 2012 until June 2017 were reviewed. VDD and insufficiency was defined by vitamin D levels of ≤20 ng/mL and 21-30 ng/mL, respectively. A total of 316 patients were enrolled on the study, of these 276 had at least 1 vitamin D level (pre or post HSCT) and 192 patients had two levels (pre and post HSCT). Patient characteristics and survival graphs are shown in Table 1, Figure 1 and 2 respectively. Severe chronic GvHD was more commonly seen in patients with VDD (p=0.0237). There was no correlation of VDD with the rate of infections (viral, bacterial or fungal), length of hospitalization, neutrophil engraftment, graft failure, or acute GvHD; there were more relapses in patients with normal Vitamin D levels. This retrospective study found that patients with VDD have a slightly higher incidence of severe chronic GvHD, which may explain the lower relapse rate in the VDD group, higher relapse rate in those with normal vitamin D levels but no correlation with all other patient outcomes after HSCT. A small sample size, variability in the accuracy of the assay used to test for vitamin D levels may be some of the limitations. A larger prospective study is needed to help understand the role of vitamin D in children undergoing allogeneic HSCT.