Cause-specific mortality among patients with epilepsy: results from a 30-year cohort study

Abstract

Purpose: Death rates of patients with epilepsy are two to three times higher than expected. The aim of our study was to further delineate the causes and the patterns of premature death in patients with epilepsy.

Methods: We included all patients who were prospectively enrolled between 1970 and 1999 in our epilepsy outpatient clinical database. Patients were followed until death or December 31, 2003. Standardized mortality ratios (SMRs) were calculated using reference rates from the same region.

Key findings: After 48,595 person years of follow-up, 648 of 3,334 patients had died, resulting in an overall SMR of 2.2 (95% confidence interval [CI] 2.0-2.4). The highest SMRs were for patients aged 26-45 years (6.8, 95% CI 3.8-11.2) and with symptomatic epilepsies (3.1, 95% CI 2.3-4.9); those for cryptogenic causes (2.2, 95% CI 1.6-3.1) were also elevated, whereas those for idiopathic causes were not increased (2.7, 95% CI 0.7-7.0) after 2 years of follow-up. SMRs for patients with persistent seizures (3.3, 95% CI 2.6-4.4) were higher than those for seizure-free patients (1.4, 95% CI 0.8-2.3). The highest cause-specific SMRs were for epilepsy (91.6, 95% CI 66.3-123.4), brain tumors (22.7, 95% CI 15.7-31.8), and external causes (2.4, 95% CI 1.8-3.3) at end of study period.

Significance: Epilepsy patients have a higher-than-expected risk of death throughout life and especially during the first 2 years following diagnosis. Standardized mortality rates were especially high in younger patients and in patients with symptomatic epilepsies. Persistent seizures are strongly related to excess mortality.