Supplementary Material for: Excess mortality in adults and adolescents with epilepsy, view from a 10-year nationwide cohort

Introduction: People with epilepsy present an excess risk of mortality, but questions remain regarding the underlying causes and risk distribution. Here, we estimated the excess mortality by age and sex among adults and adolescents with epilepsy in France and identified their main causes. Methods: A national cohort study was conducted between 2009 and 2019, with adults and adolescents aged between 12 and 60 years and having at least one hospitalization, assurance record, or delivery of anti-seizure medication linked to epilepsy on the French National Health Data System (SNDS). Mortality rates and standardized mortality ratios (SMR) were estimated according to age and sex. Specific causes of death from death certificates were also explored. Results: Between 2009 and 2019, 619,753 patients were included, of whom 60,033 (9.7%) died during follow-up, corresponding to a mortality rate of 9.55 [9.30; 9.79] per 1000 person-years. Compared with the general population, people with epilepsy had a 3.33-fold higher risk of death [3.24; 3.41], with a higher risk in women than in men, with SMRs of 4.11 [3.94; 4.29] and 2.99 [2.90; 3.09], respectively. Excess mortality was found for all causes of death, particularly neurological causes. Women with epilepsy presented a higher excess risk of death than men, especially between 20-40 years old. Conclusion: Our findings provide further evidence of increased mortality in patients with epilepsy. Remarkably, we found major differences according to sex, which have been largely overlooked so far. The fact that young women with epilepsy are at risk poses additional clinical and societal challenges.