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

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.

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).

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).

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.