Prevalence, Predictors, and Gender-Based Risk Factors of Vitamin D Deficiency: A Retrospective Cross-Sectional Study

Background: Vitamin D deficiency, a widespread global health issue, significantly impacts bone health and overall physiological well-being. Despite its prevalence, the deficiency often remains underdiagnosed and untreated, particularly in regions such as South Asia, the Middle East and North Africa (MENA), Europe, and the United States, where unique cultural, environmental, and lifestyle factors exacerbate its occurrence. Methods: This retrospective cross-sectional study, conducted at the Medical City Complex in Ibb, Yemen, analyzed data from 5,407 participants over six years (2018–2024). Serum 25-hydroxyvitamin D levels were measured to classify vitamin D status as deficient (<20 ng/mL), insufficient (20–29.9 ng/mL), or sufficient (≥30 ng/mL). Demographic and clinical characteristics were evaluated using descriptive statistics, independent t-tests, and multiple linear regression to assess age- and gender-based differences in vitamin D levels. Results: Among the study population, 77.1% were vitamin D deficient, with females showing a significantly higher prevalence (62.1%) than males (15.0%). Insufficiency was observed in 11.5%, and only 11.3% had sufficient levels. Males exhibited higher mean log-transformed vitamin D levels compared to females across all age groups. Deficiency rates peaked among adults aged 19–50 years, particularly females (45.24%). Regression analysis identified age and gender as significant predictors of deficiency, with older age and female gender increasing the likelihood of deficiency. Conclusion: Vitamin D deficiency remains alarmingly high in Yemen, particularly among females and adults aged 19–50 years. These findings emphasize the need for targeted public health interventions, including supplementation, dietary modifications, and strategies to increase safe sun exposure. Gender-specific approaches are crucial to mitigating the burden of vitamin D deficiency, particularly in populations at higher risk.