Mortality in two independent First Seizure Clinic cohorts up to 20 years post epilepsy diagnosis

BACKGROUND: Excess mortality has been demonstrated in individuals with epilepsy. Here, we aimed to examine mortality in patients from two independent First Seizure Clinics (FSCs), up to 20 years after a new epilepsy/unprovoked seizure diagnosis assigned by epileptologists. Patients were also grouped according to pre-existing medical conditions and mortality in these subgroups was examined. METHODS: In this observational study, adults (≥18 years) diagnosed with epilepsy/unprovoked seizures between 2000-2010 at Austin Health and Royal Melbourne Hospital FSCs were included. FSC information regarding epilepsy and pre-existing conditions (alcohol/substance use, psychiatric disorders, cancer, cardiac and neurological) was audited and linked to the Australian National Death Index. Patient deaths were compared to population age, sex and year-specific death rates with Standardized Mortality Ratios (SMR). RESULTS: Among N = 1545 diagnosed with epilepsy/unprovoked seizures (excluding high-grade brain tumors), 282 (18%) had deceased (all-cause mortality SMR 2.0; 95%CI 1.8-2.3). Excess mortality to 15 years post-diagnosis was demonstrated at both independent FSCs. For the n = 1375 with information about pre-existing conditions, the SMR was higher for patients with ≥ 1 pre-existing condition (n = 593; 2.6, 95%CI 2.2-3.0) than for those without (n = 782; SMR 1.4, 95%CI 1.1-1.8). Among patient subgroups, reported problematic substance use (±a psychiatric disorder, n = 227) had the highest SMR (5.8; 95%CI 4.5-7.6). CONCLUSION: Both FSCs demonstrate persistent excess mortality after a new epilepsy diagnosis. Patients who report a history of previous medical conditions, particularly those with problematic alcohol/substance use are potentially important risk groups and warrant further examination. These findings contribute to patient counselling, and inform further investigation.