All-cause mortality and SUDEP in a surgical epilepsy population

Abstract

Epilepsy surgery is considered to reduce the risk of epilepsy-related mortality, including sudden unexpected death in epilepsy (SUDEP), though data from existing surgical series are conflicting. We retrospectively examined all-cause mortality and SUDEP in a population of 590 epilepsy surgery patients and a comparison group of 122 patients with pharmacoresistant focal epilepsy who did not undergo surgery, treated at Columbia University Medical Center between 1977 and 2014. There were 34 deaths in the surgery group, including 14 cases of SUDEP. Standardized mortality ratio (SMR) for the surgery group was 1.6, and SUDEP rate was 1.9 per 1000 patient-years. There were 13 deaths in the comparison group, including 5 cases of SUDEP. Standardized mortality ratio for the comparison group was 3.6, and SUDEP rate was 4.6 per 1000 patient-years. Both were significantly greater than in the surgery group (p < 0.05). All but one of the surgical SUDEP cases, and all of the comparison group SUDEP cases, had a history of bilateral tonic-clonic seizures (BTCS). Of postoperative SUDEP cases, one was seizure-free, and two were free of BTCS at last clinical follow-up. Time to SUDEP in the surgery group was longer than in the comparison group (10.1 vs 5.9 years, p = 0.013), with 10 of the 14 cases occurring >10 years after surgery. All-cause mortality was reduced after epilepsy surgery relative to the comparison group. There was an early benefit of surgery on the occurrence of SUDEP, which was reduced after 10 years. A larger, multicenter study is needed to further investigate the time course of postsurgical SUDEP.

Keywords: Epilepsy surgery; Epilepsy surgery mortality; SUDEP; Standardized mortality ratio.

Figure 1:

Comparison of SUDEP rates between groups over time. SUDEP rates=deaths/1000 patient-years and 95% confidence intervals over time in the surgery (dark grey) and comparison (light grey) groups. The rate in the surgery group is notably low and stable through 10 years of follow up, then rises after the 10-year mark. The SUDEP rate in the comparison group is immediately higher and remains relatively stable across the entire follow up period. The difference between SUDEP rates in the surgery and comparison groups are significant at 0–2 years (cases: 1156.6 patient-years and 3 SUDEP deaths, comparison group 237.7 patient-years and 2 SUDEP deaths, chi-square test, p=0.01) and 5–10 years (cases: 7371.7 patient-years and 14 SUDEP deaths, comparison group 1096 patient-years and 5 SUDEP deaths, chi-square test, p=0.04) after Bonferroni correction (asterisks).