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

Abstract

Clinical validation studies of seizure detection devices conducted in epilepsy monitoring units (EMUs) can be biased by the artificial environment. We report a field (phase 4) study of a wearable accelerometer device (Epi-Care) that has previously been validated in EMUs for detecting bilateral tonic-clonic seizures (BTCS). Seventy-one patients using the device (or their caregivers) completed the modified Post-Study System Usability Questionnaire. Median time patients had been using the device was 15 months (range = 24 days-6 years). In 10% of cases, patients stopped using the device due to reasons related to the device. The median sensitivity (90%) and false alarm rate (0.1/d) were similar to what had been determined in EMUs. Patients and caregivers were overall satisfied with the device (median = 5.5 on the 7-point Likert scale), considered the technical aspects satisfactory, and considered the device comfortable and efficient. Adverse effects occurred in 11%, but were only mild: skin irritation at the wrist and interference with home electronic appliances. In 55% the device influenced the number of seizures logged into the seizure diary, and in 40% it contributed to fewer seizure-related injuries. This field study demonstrates the applicability and usability of the wearable accelerometer device for detecting BTCS.

Evaluation of a collar‐mounted accelerometer for detecting seizure activity in dogs

“…It is likely that a better sensitivity could have been achieved at the expense of a higher false positive rate. As it is, the daily false positive detection rates seen during our study were over an order of magnitude lower than those reported with the use of wrist‐worn devices in the home environment . Acceptable values for sensitivity and false detection rates for a device to be used to detect seizures in dogs have not been established.…”

“…Initial validation of the technology was performed in hospitalized patients admitted to long‐term video‐electroencephalography (EEG) monitoring units, during which all seizure activity was confirmed by EEG and all movements recorded, with reported sensitivity ranging from 85 to 100% and a false detection rate of 0.2‐1/day . A subsequent field study designed to evaluate the use of the device in the home environment reported a mean sensitivity of 85% and a mean false detection rate of 1.4/day . A major objective for use of these devices in humans is the detection of severe nocturnal seizures, in order to enable intervention and lead to the prevention of sudden unexpected death in epilepsy.…”

“…Video recordings would similarly be required to discern activities that induce false detections in dogs, and without such information the cause of the false detections identified in our study cannot be further characterized. False alarms in humans are attributed to specific repetitive activity patterns such as tooth brushing, playing games, hand shaking, dancing, and clapping . Another factor that may have also contributed to the dog‐to‐dog variability is the limited size of the training set.…”

“…This concern is shared by caregivers of humans with epilepsy, and has led to the recent FDA approval of a wrist‐worn, 3‐dimensional accelerometer as a seizure monitoring device in adults with epilepsy (Embrace 2, Empatica Inc, Milan, Italy). Accelerometers are able to reliably detect generalized tonic‐clonic seizures in humans and the devices have been designed to immediately alert caregivers when a seizure is detected.…”

Seizure detection and mobile health devices in epilepsy: Update and future developments

“…Surface EMG is typically used for detecting convulsive seizures, with 2 large-scale blinded prospective studies demonstrating high sensitivity (76%-100%) with average false-alarm rate ranging from 0.7 to 2.5/24 h. 7 Movement-based GTCS detection, primarily using accelerometry sensors, is associated with highly variable sensitivity (31%-95%) and positive predictive value (4%-60%) across video-EEG studies, whereas a field study reported even lower sensitivity (14%). 8 Conversely, 2 other field studies with high sensitivity are reported in this supplement: one using accelerometry showed a median sensitivity of 90% and a false alarm rate of only 0.1/d for GTCS detection, 10 whereas another one using video-only in a residential care setting reported 100% sensitivity and a median false alarm rate of 0.78 per night. 11 Multimodal seizure detection is currently characterized by various sensing methods and highly variable sensitivity (4%-100%) and rate of false alarms (0.25-20 per 8 hours).…”