Reliable detection of generalized convulsive seizures using an off-the-shelf digital watch: A multisite phase 2 study

Objective: The aim of this study was to develop a machine learning algorithm using an off-the-shelf digital watch, the Samsung watch (SM-R800), and evaluate its effectiveness for the detection of generalized convulsive seizures (GCS) in persons with epilepsy. Methods: This multisite epilepsy monitoring unit (EMU) phase 2 study included 36 adult patients. Each patient wore a Samsung watch that contained accelerometer, gyroscope, and photoplethysmographic sensors. Sixty-eight time and frequency domain features were extracted from the sensor data and were used to train a random forest algorithm. A testing framework was developed that would better reflect the EMU setting, consisting of (1) leave-one-patient-out cross-validation (LOPO CV) on GCS patients, (2) false alarm rate (FAR) testing on nonseizure patients, and (3) “fixed-and-frozen” prospective testing on a prospective patient cohort. Balanced accuracy, precision, sensitivity, and FAR were used to quantify the performance of the algorithm. Seizure onsets and offsets were determined by using video-electroencephalographic (EEG) monitoring. Feature importance was calculated as the mean decrease in Gini impurity during the LOPO CV testing. Results: LOPO CV results showed balanced accuracy of.93 (95% confidence interval [CI] =.8–.98), precision of.68 (95% CI =.46–.85), sensitivity of.87 (95% CI =.62–.96), and FAR of.21/24 h (interquartile range [IQR] = 0–.90). Testing the algorithm on patients without seizure resulted in an FAR of.28/24 h (IQR = 0–.61). During the “fixed-and-frozen” prospective testing, two patients had three GCS, which were detected by the algorithm, while generating an FAR of.25/24 h (IQR = 0–.89). Feature importance showed that heart rate-based features outperformed accelerometer/gyroscope-based features. Significance: Commercially available wearable digital watches that reliably detect GCS, with minimum false alarm rates, may overcome usage adoption and other limitations of custom-built devices. Contingent on the outcomes of a prospective phase 3 study, such devices have the potential to provide non-EEG-based seizure surveillance and forecasting in the clinical setting.