Incidence of Hypocalcemic Seizures Due to Vitamin D Deficiency in Children in the United Kingdom and Ireland

Context: Anecdotal reports suggest that increasing numbers of children in the UK are presenting with clinical manifestations of vitamin D deficiency (VDD). However, the epidemiology of symptomatic VDD is largely undetermined; existing studies are limited to local case series, and national incidence estimates of disease burden are lacking. Objective: To estimate the incidence of hypocalcaemic seizures secondary to VDD in children in the UK and Ireland, and describe the demographic and clinical features of cases. Design and Setting: Prospective, population-based active surveillance study using the established British Paediatric Surveillance Unit (BPSU) methodology. Population: Children aged 0-15 years, resident in the UK and Ireland, who developed a hypocalcaemic seizure due to VDD between September 2011 and September 2013. Main Outcome Measure: Overall incidence of hypocalcaemic seizures due to VDD in children age 0-15, and incidence stratified by age, sex, and ethnicity. Results: Ninety one confirmed or probable cases were reported, equating to an overall annual incidence of 3.49 per million children age 0-15 years (95% CI: 2.81-4.26). Incidence was significantly greater in males compared to females, in infants compared to older children, and in children of South Asian or Black ethnicity compared to children from white ethnic backgrounds. Conclusions: Current implementation of public health policy in the UK is not successful in preventing children from developing one of the severe manifestations of VDD. Further studies are required to evaluate the epidemiology of symptomatic VDD more broadly in order to guide future public health policy decisions.