Childhood epilepsy recorded in primary care in the UK.

OBJECTIVE: To examine temporal trends in the incidence of epilepsy recorded in UK primary care and to evaluate the impact of recent efforts to improve the specificity of diagnosis in children.
DESIGN: Birth cohort study using primary care data from The Health Improvement Network, which includes a representative sample of the UK population of approximately 5%.
METHODS: We identified epilepsy recorded in primary care using relatively specific through to relatively sensitive indicators to identify epilepsy. Incidence estimates were based on 344 718 children aged 0-14 years with 1 447 760 years' follow-up between 1994 and 2008. Trends in cumulative incidence were explored with stratified analysis by year-of-birth. Trends in annual incidence were investigated using Poisson regression with adjustment for age, gender and deprivation.
RESULTS: Cumulative incidence of recorded epilepsy at age 5 years ranged from 0.38% to 0.68% and annual incidence ranged from 71 to 116/100 000 person-years-at-risk, depending on the indicator used to identify epilepsy. With the most specific indicator for epilepsy, cumulative incidence was 33% lower among children born in 2003-2005 than in children born in 1994-1996, and annual incidence declined by 4% per annum between 2001 and 2008, after adjusting for age, gender and deprivation. Using a more sensitive indicator for epilepsy, the equivalent declines were 47% in cumulative incidence and 9% in annual incidence.
CONCLUSIONS: The decline since the mid-1990s in epilepsy recorded in primary care may be due to more specific diagnosis, cessation of treatment for some forms of epilepsy, reduced exposure to risk factors or all of these factors.