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Low serum vitamin D levels are becoming increasingly implicated in infections, pulmonary disorders, cancer incidence and autoimmune conditions. Their role in allogeneic haematopoietic stem cell transplantation (alloHSCT) remains unclear, with some studies showing deficiency to be associated with lower overall survival (OS) and increased graft versus host disease (GVHD) rates, while other studies show no differences in OS or GVHD rates. We investigated the relationship between low vitamin D levels pre-alloHSCT and post-transplant outcomes (OS, progression-free survival [PFS], non-relapse mortality [NRM], relapse and acute and chronic GVHD).
Methods
We reviewed 492 alloHSCT recipients who had pre-transplant vitamin D results available. Data on dates of death, last follow-up, disease progression/relapse, disease risk index (DRI) and acute and chronic GVHD status were collected. Patients were categorised as replete (25-OH-Vit D ≥ 50nmol/L or on replacement therapy) or deficient (25-OH-Vit D < 50nmol/L). Subgroup analysis was performed on B-cell non-Hodgkin lymphoma patients (B-NHL).
Results
The vitamin D-deficient cohort had a higher mortality rate compared to the replete group. This reduction in survival was maintained in the multivariate analysis (HR 1.5, 95% CI 1.1-2.0, P=0.013). There were no significant differences in NRM, PFS, acute/chronic GVHD, or relapse rates between the two groups. No significant differences were noted with any of these outcomes in the 123 B-NHL patients. There was no association between 25-OH-Vit D levels and DRI.
Conclusion
Vitamin D deficiency appears associated with increased mortality in alloHSCT recipients. The mechanisms of this finding remain unclear. GVHD rates did not appear to be affected by deficiency. Further research looking at whether immunomodulatory effects of vitamin D are responsible for the survival differences noted in our study, and previously reported studies, is required.