Prevalence, outcomes, and complications of vitamin D deficiency among patients with multiple myeloma: Nationwide burden of disease.

Multiple myeloma (MM), constituting 10% of hematological malignancies, poses significant morbidity and mortality, especially with skeletal involvement. Bisphosphonate use in MM may lead to severe hypocalcemia due to vitamin D deficiency (VDD), exacerbating bone-marrow plasma cell burden. We aimed to assess VDD prevalence and its impact on outcomes in MM patients. A retrospective cross-sectional analysis (2008-2018) of nationwide inpatient data identified adult MM hospitalizations with VDD using ICD-10-CM codes. Univariate and multivariate analyses were conducted to evaluate prevalence, demographics, and outcomes, with significance set at p < 0.05. Among 330,175 MM hospitalizations, 3.48% had VDD. VDD was more prevalent among 50-75 year olds (61.72% vs 59.74%), females (53.36% vs 44.34%), Blacks (23.34% vs 22.94%), Whites (65.84% vs 65.79%), higher income brackets (26.13% vs 23.85%), and those with comorbidities like hypertension (71.12% vs 69.89%), dyslipidemia (42.47% vs 34.98%), obesity (13.63% vs 10.19%), and alcohol abuse (1.61% vs 1.34%). In regression analysis, VDD in MM patients correlated with higher morbidity (adjusted odds ratio (aOR): 1.24, 95% confidence interval (95% CI): 1.14-1.36) and major disability (aOR: 1.26, 95% CI: 1.20-1.30). MM patients with VDD exhibit worse outcomes, underscoring the importance of recognizing and managing VDD promptly. Further prospective studies are needed to validate our findings and explore the impact of vitamin D supplementation on MM patient outcomes.