Sudden Death Risk in Epilepsy May Drop Over Time

Pauline Anderson

December 03, 2018

NEW ORLEANS — Risk for sudden unexplained death in epilepsy (SUDEP) appears to change over time; in many cases, the risk diminishes from higher to lower, new research suggests.

Dr Neishay Ayub

Investigators found that almost 60% of patients who were initially categorized as being at high risk for SUDEP were in a lower risk category after 3 years and that fewer than 25% of patients who were initially in a low risk category were at increased risk over time.

"A low-risk patient is likely to remain low risk, whereas higher-risk patients, defined as those having at least one generalized seizure a year, may leave their initial risk stratification," study investigator Neishay Ayub, MD, clinical neurophysiology and epilepsy fellow, Massachusetts General Hospital, Boston, told Medscape Medical News.

SUDEP risk is something that physicians and patients "should think about yearly," said Ayub, "and patients should receive appropriate treatment and counseling."

The study was presented here at the American Epilepsy Society (AES) 2018 Annual Meeting.

Patient-Centered Tool

SUDEP is a significant contributor to epilepsy deaths, but it is poorly understood. What researchers do know is that certain factors are associated with SUDEP risk, including the presence and frequency of generalized tonic-clonic seizures.

Over the past few years, a number of online electronic seizure diary systems have been created. One of these, the Seizure Tracker, is a patient-reported database that now includes seizure information on 14,000 users, about half of whom are younger than 18 years.

Dr Daniel Goldenholz

"It's one of the largest databases of its kind in the world," study coinvestigator Daniel M. Goldenholz, MD, PhD, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, told Medscape Medical News.

The database was created about 11 years ago by a father whose son had drug-resistant epilepsy.

The Seizure Tracker tool incorporates voice-activated technology and unique within-app features. For example, for women, it includes menstrual cycle tracking and will soon have a birth control/pregnancy feature. It also has a diet function that helps track seizure activity in relation to food intake.

The application also includes a vagus nerve stimulator (VNS) input, which allows patients to enter their VNS settings and record VNS use.

Patients have the option of allowing their physician to access this electronic seizure diary.

"This tool allows everyday people, caregivers, or patients themselves to keep track of information about their seizures, about their triggers, about their medications, about their vagal nerve stimulator, and other things related to their epilepsy, all in one place," said Goldenholz.

Expanded Tracker Access

Access to the tracker tool has expanded over time. Initially, it was available only through a website. Subsequently, apps for iOS and android devices became available, and Apple Watch and Amazon have now been added as entry points.

"So there are a lot of mobile, wearable, and digital devices that you can use, but 100% of it is patient-reported data," said Goldenholz.

In a recent article in Neurology, Goldenholz and colleagues compared the Seizure Tracker to two other mobile epilepsy self-management tools. The Seizure Tracker platform, they said, offers a clear interface with few superfluous features.

"We found its graphical summary reports to be among the most informative relative to other similar applications, allowing for details such as medication dose changes to be clearly marked on the charts," they wrote.

No seizure tracker tool is perfect, though, said Goldenholz. He recommended that patients learn for themselves what works best for them.

For the new study, researchers collected data on seizures from 12,402 Seizure Tracker users from December 2007 to February 2018. They analyzed over 1.4 million seizures and grouped these into generalized seizures (defined as tonic clonic or secondarily generalized) and other seizures.

Risk Categories

For each user and for each year, the investigators calculated the number of generalized seizures and designated the patient as being at low risk for SUDEP (no generalized seizures), medium risk (1-2 generalized seizures), or high risk (three or more generalized seizures).

Ayub noted that although the low-risk group experienced no generalized seizures during the course of a year, patients in this category would experience other types of seizures that are not associated with SUDEP risk.

The researchers used Kaplan-Meier survival curves to assess the probability of SUDEP risk diverging from the initial risk stratification.

The analysis found that the vast majority of patients who began at low risk for SUDEP remained in this category. At 3 years, 77.3% of patients who initially were at low risk remained in this risk category.

Most of those who began at medium or high risk for SUDEP were no longer categorized as such either because their risk for SUDEP changed or they stopped using the app. Only 40.8% of people who were initially categorized as being at high risk for SUDEP remained in that risk category.

The researchers could not determine whether those who moved from the high-risk category ended up in the medium- or low-risk group.

However, Goldenholz noted that there weren't many people in the medium-risk category.

"For some reason, the group of people identified as medium risk was small to begin with and quickly got very small, so it was a bit harder to draw conclusions about what that small group was doing," he said.

Risk Is Fluid

It is currently impossible to know whether use of the the tracker led to a lowering of patients' risk for SUDEP or whether those who used the seizure tracker were somehow different from those who did not use it.

"Anecdotally, in my clinic and when I speak to my colleagues, it's pretty hard to get the average patient to keep track of anything, on paper or on a computer," said Goldenholz. "Are these people who are tracking seizures special people, or are they more digitally savvy? We don't know."

Goldenholz noted that many of the patients who use the tool are older adults.

Physicians tend to want to put patients into "boxes" — to label them, for example, as "risky" because they're not doing well or "safe" if they respond to treatment — but this is not a good practice, said Goldenholz.

"It makes things mentally clean and simple for providers, but it certainly can be quite frightening and disheartening for patients to think that whatever box they were put in, that's their box. This study really says that, no, the box you're in today is not necessarily the box you're in next year."

The literature suggests that patients look to their physician for advice on SUDEP risks, although some providers may not know the best way to provide that advice, said Arub.

One of the drawbacks of using the database is that some of those who use it may not actually have epilepsy, said Goldenholz.

"One could argue that people who think they have epilepsy use the software but in fact might not have the disease. This is a fundamental problem when using patient-reported data," he said.

Select Group

Commenting on the study for Medscape Medical News, AES President Shlomo Shinnar, MD, PhD, Montefieore Medical Center, Albert Einstein College of Medicine, New York City, said, "It's interesting preliminary work."

However, the study is retrospective, and people who sign onto Seizure Tracker "are a select group," said Shinnar. "It's not that the data are not valid; it's that one has to remember that these users are not necessarily representative."

Shinnar also emphasized that researchers do not know enough about SUDEP risk factors because it's relatively rare.

"The authors are assuming that if you change from four seizures a year to two seizures a year, that that changes your SUDEP risk, but we don't know that. The only thing that has been completely established as a risk factor is being seizure free, which either eliminates or major league reduces your SUDEP risk," he said.

Shinnar noted that some patients appear to do very well after undergoing epilepsy surgery, "and then suddenly, they become intractable."

Although this new study provides useful new information and some patients will be reassured by it, "we need to be careful; low risk is not a zero risk," he said.

The Harvard T. H. Chan School of Public Health provided funding for the study. Dr Arub, Dr Goldenholz, and Dr Shinnar have disclosed no relevant financial relationships.

American Epilepsy Society (AES) 2018 Annual Meeting. Abstract 2.158, presented December 2, 2018.

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