Impact of Vitamin D Deficiency on Survival for Patients Received Haploidentical Hematopoietic Stem Cell Transplantation (haplo-HSCT)

Background Beyond its role in bone health, vitamin D is known to have immunomodulatory effects including cell proliferation, differentiation and apoptosis. Delays in immune reconstitution following HSCT increase transplant-related toxicity. Several studies have explored the role of vitamin D deficiency after HSCT with mixed results regarding its impact on survival outcomes. Our aim in this study was to examine the impact of vitamin D deficiency prior to HSCT on transplant outcomes in patients who received a haplo-HSCT. Methods This retrospective study included consecutive patients who underwent haplo-HSCT at our institution between 02/2009 and 01/2021. Primary objectives were to assess progression-free survival (PFS) and overall survival (OS) by vitamin D status at the time of transplant. Vitamin D deficiency was defined as vitamin D levels < 20 nmol/L within 6 months prior to transplant. Survival estimates were calculated using Kaplan-Meier method. Proportional cox hazards analysis was used to adjust for multivariable analysis (MVA). Results Four-hundred and eighty-four patients out of 508 patients had vitamin D checked at baseline and were included in the final analysis. Table 1 summarizes patient, disease, and transplant characteristics for all study patients, and by vitamin D status. Median age for all study patients was 48 (18-72) years, of which 237 (49%) had vitamin D deficiency and 247 (51%) had normal vitamin D level. Overall, the two groups were comparable, except that patients in the vitamin D deficiency group were younger in age. Furthermore, we adjusted for disease subtype heterogeneity by using the validated disease risk index (DRI). With a median follow-up of 35.4 (range, 1.4-132.8) months, the 3-year PFS and OS for all study patients were 44% and 48%, respectively. The respective 3-year PFS and OS for the vitamin D deficiency group were 42% and 47% compared to 46% and 50% for patients with adequate vitamin D (p=0.773 for PFS; p=0.704 for OS). Furthermore, we found no difference in non-relapse mortality at 3 years (each for 30%; p=0.6682). Univariate analysis (UVA) was performed for the following variables: vitamin D, age, gender, KPS, DRI, HCT-CI, and intensity of conditioning regimen. MVA included only the factors with p value