Updates on Prevalence of Vitamin D Deficiency and the Associated Outcomes in Sickle Cell Disease Patients: A Systematic Review

Abstract

Objectives: To evaluate and synthesize the latest evidence on the prevalence of vitamin D deficiency (VDD) in patients with sickle cell disease (SCD).Methods: A total of 866 pertinent publications were found after a comprehensive search across four databases. 53 full-text publications were examined after duplicates were eliminated using Rayyan QCRI and relevance was checked; eight studies finally satisfied the requirements for inclusion. Results:We included eight cross-sectional studies with a total of 1961 SCD patients, of whom 674 (34.4%) were males. There is a variation in VDD prevalence, which ranged from 7.6% to 67%, with an overall prevalence of 48.5%. Alarmingly high rates were observed in certain regions, particularly among children. Key findings suggest that VDD in SCD patients is linked to low dietary intake, inadequate supplementation, and poor cutaneous synthesis of vitamin D. While some studies did not identify direct short-term correlations between vitamin D levels and SCD complications, others reported better hematological profiles with sufficient vitamin D. VDD is associated with increased risks of bone health issues, recurrent infections, vaso-occlusive crises, acute pain episodes, anemia, and the need for blood transfusions. Conclusion:This review shows a high prevalence of VDD among SCD patients, though it varies across regions and demographics. While the link between VDD and complications of SCD is inconsistent, there is a relationship between adequate vitamin D levels and improved clinical outcomes. The findings underscore the importance of routine screening, dietary supplementation, and tailored interventions. Longitudinal studies are needed in the future to clarify causality and to inform evidence-based guidelines for managing VDD in SCD patients.