Abstracts

Rationale: Understanding the relationship between epilepsy and socioeconomic deprivation may help narrow the treatment gap and assist healthcare resource planning. Anonymised primary care electronic health records and WIMD deprivation index information are stored as part of the Secure Anonymised Information Linkage system at Swansea University, UK. WIMD is an index of socioeconomic deprivation and is calculated from a range of indicators from eight domains: income; employment; health; education; housing; access to services; environment and community safety. We investigated the relationship between socioeconomic deprivation and epilepsy incidence and prevalence by electronically linking the primary care records with the corresponding deprivation index scores.Methods: We retrospectively reviewed 13.3 million patient years of electronic health records from 2000 to 2010. Cases of epilepsy were defined as patients with a diagnosis of epilepsy having had at least two prescriptions of anti-epileptic drugs within the six months following diagnosis. For each case the deprivation index decile was recorded. The prevalence on 1st January and the incidence was calculated for each year between 2000 and 2010. We also recorded the change in deprivation index nine years after initial diagnosis for a cohort of people with incident epilepsies in 2000 and 2001. Results: The prevalence of epilepsy (mean prevalence = 0.7% or 8523 cases) is positively correlated with deprivation index decile and ranged from 0.46% in decile 1 (least deprived) to 1.1% in WIMD decile 10 (most deprived) (correlation coefficient, = 0.96 p<0.001) see also figure 1. The incidence of epilepsy (mean = 28 /100 000/year or 337 cases/year) was also positively correlated with deprivation index decile and ranged from 19/100 000/year in decile 1 to 38/100 000/year in decile 10 ( =0.97, p<0.001) see also figure 2. There was no significant change in deprivation index decile nine years after a new diagnosis of epilepsy (mean difference=0.01, p=0.94, 95% confidence interval -0.20,0.21).Conclusions: Epilepsy incidence and prevalence are strongly associated with socioeconomic deprivation. Epilepsy is a heritable trait and this may underlie the patterns described. Post-diagnosis social drift is a less likely explanation given that incidence as well as prevalence are associated with increased deprivation and given that a new diagnosis of epilepsy does not change the deprivation score nine years after diagnosis.