Their user-friendliness and relatively low cost made commercial wearable devices increasingly popular. However, their marketing is not conditional on any attestation of accuracy of the collected data.

Demonstrating the reliability of signals detected by commercial devices would provide physicians and researchers with a considerable amount of data on which to test their hypotheses.

The objective of the study conducted by Benedetti and colleagues was to evaluate the accuracy of the heart rate detected by one of the most widely used commercial wrist-worn devices (Fitbit ChargeHR™) compared to that measured by electrocardiography, which is the most reliable and frequently used method.

Results showed that the accuracy of heart rate measured by Fitbit ChargeHR™ relies on participant’s state of alertness. In particular, the data collected during sleep are very accurate, while the data collected during wakefulness are less reliable. This difference is possibly related to limb movements, which can critically interfere with heart rate measurement, for instance by moving the sensor away from the wearer’s skin.

Overall, the study demonstrates that caution is needed in the interpretation of data acquired using commercial devices and that the validation is a necessary process to understand their potential use in a clinical or research setting.