Prevalence of Vitamin D Deficiency and Insufficiency and Its Risk Factors in Paediatric Patients with Epilepsy on Anti-epileptic Drugs

Objective: The aim of our study is to evaluate the prevalence of vitamin D deficiency and insufficiency in children with epilepsy on anti-epileptic drugs (AED) in a regional hospital in Hong Kong. In addition, we would evaluate the possible risk factors of vitamin D deficiency and insufficiency in these patients. Method: A cross-sectional study was conducted in a regional hospital in April to May 2018 on paediatric patients who were on AED for at least one year. Review of medical records, anthropometric measurements, dietary and sunlight exposure behaviour assessments and blood tests (vitamin D assay and bone profile) were performed. Vitamin D deficiency is defined as serum 25- hydroxyvitamin D (25-OHD) level <30 nmol/L and insufficiency as 25-OHD level between 30- 50 nmol/L. Results: Seventy-one children aged 3 to 18 years old were recruited into the study. The prevalence of vitamin D deficiency and insufficiency were 16.9% ( 12/71) and 52.1% (37/71) respectively. The two groups added up to a prevalence of 69.0% (49/71). In logistic regression analysis, the lack of holiday trip abroad within past three months (odds ratio 0.1, 95% confidence interval 0.02-0.73) was found to be a statistically significant independent risk factor for vitamin D deficiency and insufficiency. Conclusion: Vitamin D deficiency and insufficiency are highly prevalent in paediatric patients with epilepsy on AEDs in Hong Kong. However, it is similar to the prevalence found in healthy adolescents. This suggests that adolescents taking AEDs may not have an additional risk in lowering their vitamin D levels in this locality. We therefore would not advocate for routine screening for vitamin D level in adolescent epilepsy patients on AEDs in this locality, as it will not be cost-effective. Given that this is a cross sectional study, further interventional studies exploring the role of holiday trip abroad on vitamin D levels in paediatric epilepsy patients are warranted to substantiate a causality relationship.