How Common Is Sudden Unexpected Death in Epilepsy?

Sudden Unexpected Death  in Epilepsy (SUDEP)

•SUDEP: “Sudden, unexpected, witnessed or unwitnessed, non-traumatic, and non-drowning death of patients with epilepsy with or without evidence of a seizure, excluding documented status epilepticus, and in whom postmortem examination does not reveal a structural or toxicologic cause for death.”[1]

•Among neurological conditions, SUDEP ranks second only to stroke for years of potential life lost[2]

•Studies show wide variation in SUDEP rates, making actual incidence difficult to ascertain 

Nationwide Swedish Study of SUDEP[3]

•Nationwide, population-based, cohort study of SUDEP incidence at all ages[3]

•Used Swedish National Patient Registry for 1998-2005 to id epilepsy cases (n= 57,775)

•Used the National Cause of Death Registry to id epilepsy patients who died in 2008 (n=1890)

•Reviewed death certificates, medical charts, police and autopsy reports for SUDEP cases

•Divided SUDEP into definite, probable, and possible subgroups

•Incidence rates for pooled definite and probable SUDEP are per 1000 person-years

SUDEP Incidence Higher in Boys and Men

•5.2% of all deaths among epilepsy patients in 2008 were from SUDEP

•99 met criteria for SUDEP, of which 67 were men

•SUDEP incidence higher in men (1.41) than in women (0.96)

•All SUDEP cases in children under age 16 were boys

Risk in Older People Higher than Thought

SUDEP incidence similar across age groups:

     •<16 years: 1.11

     •16-50: 1.13

     •>50: 1.29

•Relative contribution of SUDEP to overall deaths:

     •<16 years: 36%

     •16-50: 21.3%

     •>50: 3.3%

•Lower relative contribution in older patients likely due to increased death from other causes 

SUDEP Linked to Treatment-Resistant Epilepsy in Youth

•36% of deaths in 0-15 year-olds were from SUDEP

•All children who died from SUDEP had treatment-resistant epilepsy

•Highlights the importance of early consideration for epilepsy surgery in children

SUDEP Linked to Psychiatric Comorbidities

•SUDEP incidence over twice as high in patients with psychiatric comorbidities vs without (1.95 vs 0.89, respectively; RR 2.18)

     •SUDEP incidence 5 times higher in women with psychiatric comorbidities vs women without (2.34 vs 0.45, respectively; RR 5.15)

Death Certificates Poor Means to ID SUDEP

•Of 99 cases of SUDEP, death certificates listed SUDEP as the immediate cause of death in only 1 case

     •Seizures listed as immediate cause of death in 18 cases

     •Epilepsy listed as immediate cause of death in 8 cases

•Epilepsy was listed anywhere on the death certificate in just 63% of SUDEP cases 

Study Limitations

     •Chart review showed over 90% of epilepsy cases id’d with ICD codes

     •Study may underestimate SUDEP by about 10%

•Small number of SUDEP cases

•Results may generalize only to countries with similar living conditions and healthcare as Sweden

Take Home Points

•National Swedish study suggests SUDEP risk is underestimated

•Incidence is higher than expected in boys; older people; and people with psychiatric comorbidities, especially women

•SUDEP linked to treatment-resistant epilepsy in youth

•Studies that use death certificates to identify SUDEP may underestimate its incidence

•More information about SUDEP can be found in a practice guideline summary from the American Academy of Neurology and the American Epilepsy Society: Practice guideline summary: Sudden unexpected death in epilepsy incidence rates and risk factors. Neurology. 2017;88:1674-1680. http://www.neurology.org/content/88/17/1674.full

REFERENCES

1. Nashef L. Sudden unexpected death in epilepsy: terminology and definitions. Epilepsia. 1997;38(Suppl 11):S6–S8.

2. Thurman DJ, Hesdorffer DC, French JA. Sudden unexpected death in epilepsy: assessing the public health burden. Epilepsia. 2014;55:1479–1485.

3. Sveinsson O, Andersson T, Carlsson S, et al. The incidence of SUDEP: a nationwide population-based cohort study. Neurology. 2017 Jun 7.