title: Risk Assessment for Sudden Death in Epilepsy: The SUDEP-7 Inventory.
abstract: BACKGROUND
  Sudden unexpected death in epilepsy (SUDEP) is a major cause of death in those with drug-resistant epilepsy (DRE). There is a need for inventories and biomarkers associated with the risk for SUDEP.
  
  
  OBJECTIVE
  To explore the revised SUDEP Risk Inventory (SUDEP-7) in a cohort with DRE and determine the association with Heart Rate and other covariates.
  
  
  METHODS
  Twenty-five subjects with severe DRE were enrolled in a clinical trial for epilepsy. Baseline demographics, duration of epilepsy, seizure types, seizure frequency, seizure severity, AEDs, and vital signs were collected. Heart rate variability (HRV) was calculated from 1-h recordings of ECG. A SUDEP Risk Inventory (SUDEP-7) was administered, which included seven validated and weighted risk factors initially identified by Walczak et al. as factors associated with SUDEP risk.
  
  
  RESULTS
  The total score on the revised SUDEP-7 ranged from 1 to 7, mean = 3.4 (SD 1.8). The SUDEP Risk Inventory score was inversely correlated with RMSSD (Pearson r = -0.45, p = 0.027). The following variables were significantly associated with RMSSD: epilepsy duration (p = 0.02), age (p = 0.03), and developmental intellectual disability (p < 0.001). The correlation between RMSSD and SUDEP-7 tended to persist also after the adjustment for patient age (r = -0.40, p = 0.05). Two subjects died of SUDEP: their SUDEP-7 scores were above average and in the upper twenty-fifth and fiftieth percentiles, respectively (6 and 4, mean = 3.4).
  
  
  CONCLUSIONS
  RMSSD, a measure of low frequency HRV, was significantly associated with SUDEP Risk Inventory (SUDEP-7) scores. Using a multivariate model, the covariates of developmental intellectual disability, age, and duration of epilepsy were also significantly associated with decreased HRV. The correlation between decreased HRV and a higher SUDEP-7 score remained unchanged even after the adjustment for patient age. The results suggest that older age, greater duration of epilepsy, and the presence of developmental intellectual disability may increase the risk of SUDEP through their direct influence on decreasing the vagus nerve-mediated HRV. Further validation of the SUDEP-7 inventory is indicated.
  
  
  BACKGROUND
  ClinicalTrials.gov, NCT00871377.
authors.affiliation: Department of Neurology, University of California Los Angeles School of Medicine , Sylmar, CA , USA.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Novak
authors.affiliation: Department of Neurology, University of California Los Angeles School of Medicine , Sylmar, CA , USA.
authors.forename: Patrick R
authors.initials: PR
authors.lastname: Miller
authors.affiliation: Department of Biomathematics, University of California Los Angeles School of Medicine , Sylmar, CA , USA.
authors.forename: Daniela
authors.initials: D
authors.lastname: Markovic
authors.affiliation: Department of Cardiology, University of California Los Angeles School of Medicine , Sylmar, CA , USA ; Olive View-UCLA Medical Center , Sylmar, CA , USA.
authors.forename: Sheba K
authors.initials: SK
authors.lastname: Meymandi
authors.affiliation: Department of Neurology, University of California Los Angeles School of Medicine , Sylmar, CA , USA ; Olive View-UCLA Medical Center , Sylmar, CA , USA.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: DeGiorgio
keywords: SUDEP; SUDEP-7; epilepsy; heart rate variability; mortality; sudden death in epilepsy