False alarms in epilepsy alarms

False alarms create insecurity and irritation. Too many and you risk losing confidence in your alarm.

Thus, it is only natural to ask:

  • Can I get an alarm that does not send false alarms?

  • How many false alarms can I expect?

The short answer: No, you cannot get an alarm that does not send false alarms. On average, Epi-Care will send a false alarm every fifth day. This is the lowest number of false alarms found in a clinical trial. A large group of users experience almost no false alarms. Yet, about 15 % of our users often experience them.

All epilepsy alarms send false alarms occasionally. But, some false alarms can be avoided if you are familiar with the technology of the alarm and you can operate the alarm correctly. This article is based on two of our epilepsy alarms: Epi-Care mobile and Epi-Care free.

We know a lot about false alarms in our Epi-Care alarms

Danish and German researchers investigated Epi-Care free and Epi-Care mobile in two major clinical trials. In total, 144 people with epilepsy have tested the Epi-Care alarms. This means we have data from impartial research that shows how many false alarms you can expect.

Both tests show that the average person triggers a false alarm every five days.

 
The rate of false alarms was 0.2/day
— Detection of generalized tonic–clonic seizures by a wireless wrist accelerometer: A prospective, multicenter study
(The) false alarm rate (0.1/d) were similar to what had been determined in Epilepsy Monitoring Units (2013 test)
— User-based evaluation of applicability and usability of a wearable accelerometer device for detecting bilateral tonic–clonic seizures: A field study
 

The first study, from 2013, used video-EEG to measure seizures and false alarms. The time spent monitoring the participants during the study was relatively short, up to five days.

However, the participants in the second study, from 2018, have used their epilepsy alarms for several years. This means we have a precise idea of the number of false alarms occurring in real-life. No other epilepsy alarm has been studied for such a long time.

The rate of false alarms

Based on data of User-based evaluation of applicability and usability of a wearable accelerometer device for detecting bilateral tonic–clonic seizures: A field study

What causes alarms and false alarms?

A tonic-clonic seizure has a distinct pattern of movement with sudden muscle stiffness followed by the limbs jerking. The jerking is caused by muscles relaxing and tightening repeatedly. Epi-Care free and Epi-Care mobile uses accelerometers that measure movement to determine whether an epileptic seizure is occurring. The Epi-Care alarms doesn’t measure epilepsy, instead it measures the movements of the body.

Epi-Care free doesn’t measure epilepsy - it measures the movements of the body”

The alarm is triggered by fast rhythmic twitches. These twitches are distinctly different from everyday movements, yet, there are similarities. Sometimes, we need to make quick rhythmic movements. Such as when you brush your teeth. We can also be subjected to such movements by our surroundings, e.g. if you ride your bike on a potholed road.

In “User-based evaluation of applicability and usability of a wearable accelerometer device for detecting bilateral tonic–clonic seizures: A field study” the researchers investigated what movements caused false alarms. Here is a selection:

  • drumming with hands

  • dancing

  • bicycling

  • throwing dices

  • playing computer games

  • tooth brushing

  • clapping

  • cooking

Place the epilepsy alarm on your left hand…

... if you are right handed. Or the other way around.

The clinical trials show no difference whether the Epi-Care sensor is placed on the left or the right hand. This is an easy way to avoid false alarms caused by e.g. tooth brushing or cooking.

What alarm sends the fewest false alarms?

No one can give a proper answer to that question. Why not? It is difficult to compare epilepsy alarms. There are three good reasons:

1. Epilepsy alarms use different types of sensors. Portable sensors can measure pulse or electromyography, or the sensor uses an accelerometer to measure movement as Epi-Care alarms do. Therefore, it is difficult to compare the alarms.

2. There is no standardised method of testing epilepsy alarms. Very few studies investigate false alarms.

3. Often, epilepsy alarms are never clinically tested. You are not required to clinically test epilepsy alarms to sell them. You don’t even need to get your product approved as a medical aid before you are allowed to sell it.

All this means that there is not enough data to properly compare the various epilepsy alarms and the false alarms they send. What we can tell you is that Epi-Care mobile is the epilepsy alarms with the lowest documented number of false alarms in major clinical trials. This is apparent in the so-called meta studies where researchers attempt to compare the different alarms.

This is done in the study: Movement-based seizure detection from 2018 that compares 15 different clinical trials, of which 11 are accelerometer-based just like the Epi-Care alarms. Here the clinical trial of Epi-Care free from 2013 is highlighted as still being the one showing the fewest false alarms. And the same is seen in the “Safe and sound? A systematic literature review of seizure detection methods for personal use” where 43 clinical trials are reviewed. This study also states that Epi-Care is the epilepsy alarms with fewest false alarms.

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References:

Arends, Johan B. A. M. (2018). Movement‐based seizure detection. Epilepsia, 59(S1), 30-35. doi:10.1111/epi.14053

Beniczky, S., Polster, T., Kjaer, T. W., & Hjalgrim, H. (2013). Detection of generalized tonic–clonic seizures by a wireless wrist accelerometer: A prospective, multicenter study. Epilepsia, 54(4), e58-e61. doi:10.1111/epi.12120

Jory, C., Shankar, R., Coker, D., McLean, B., Hanna, J., & Newman, C. (2016). Safe and sound? A systematic literature review of seizure detection methods for personal use. Seizure: European Journal of Epilepsy, 36, 4-15. doi:10.1016/j.seizure.2016.01.013

Meritam, P., Ryvlin, P., & Beniczky, S. (2018). User‐based evaluation of applicability and usability of a wearable accelerometer device for detecting bilateral tonic–clonic seizures: A field study. Epilepsia, 59(S1), 48-52. doi:10.1111/epi.14051

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