Vitamin D deficiency and outcomes in pediatric hematopoietic stem cell transplantation.

BACKGROUND: Pediatric patients undergoing hematopoietic stem cell transplantation (HSCT) are frequently diagnosed with vitamin D deficiency, which may impact outcomes.

OBJECTIVES: To estimate the prevalence of vitamin D deficiency and examine its association with short-term survival in pediatric HSCT patients.

METHODS: Patients undergoing HSCT at Phoenix Children's Hospital were retrospectively identified. Routine serum 25-hydroxyvitamin D measurements were described prior to transplant and at 100 days and 1-year post-HSCT. Associations of pre-HSCT vitamin D groups (i.e., normal ≥30 ng/ml, insufficient 20-29 ng/ml, and deficient <30 ng/ml) with demographics, clinical factors, and outcomes were examined using nonparametric tests and Cox proportional hazards analyses.

RESULTS: Among 72 study subjects, the median vitamin D pre-HSCT was 26 ng/ml (range: 19-34 ng/ml). Levels were insufficient and deficient in 25 (35%) and 20 (28%) patients, respectively, with only two (3%) patients on supplemental therapy pre-HSCT. Despite supplemental therapy provided to 46 (74%) subjects, insufficient/deficient rates did not significantly change between pre-HSCT and 100 days post-HSCT, but mean vitamin D levels significantly increased by 1-year post-HSCT (P = 0.01).Vitamin D pre-HSCT was not associated with the development of acute or chronic graft-versus-host disease (GVHD) or delayed engraftment. Overall 1-year survival was significantly lower for patients with deficient (65%) compared to normal (93%) pre-HSCT vitamin D (P = 0.001).

CONCLUSION: Suboptimal vitamin D levels are common in pediatric patients scheduled to receive HSCT and are associated with lower overall 1-year survival. Further study is warranted to delineate the mechanisms underlying the role of vitamin D in successful HSCT.