Table 2.
Features of the wearable devices (WDs) the included studies focused on (N=69).
| Features | Values, n (%) | References | |
| Target condition | |||
| Depression | 44 (64) | [19,20,23-28,30,32,34-38,42,43,46-53,57,59,60,62,64-71,73,77,79,82-84,86] | |
| Anxiety | 17 (25) | [21,22,31,39-41,45,58,61,72,74,75,78,80,81,85,87] | |
| Anxiety and depression | 8 (12) | [29,33,44,54-56,63,76] | |
| Status of WDa | |||
| Commercial | 63 (91) | [19-38,40-43,46-60,62-71,73-81,83-87] | |
| Noncommercial | 7 (10) | [39,44,45,61,72,82,87] | |
| Name of WDb | |||
| Actiwatch AW4 (Cambridge Neurotechnology) | 17 (25) | [19,20,32,34-36,42,43,47,48,62,65,68-71,86] | |
| Fitbit series (Fitbit Inc) | 13 (19) | [25,26,30,31,33,38,50,52,59,63,73,80,84] | |
| Empatica series (Empatica Inc) | 7 (10) | [27,37,58,66,75,78,85] | |
| 3-Space Sensor (Yost Labs) | 4 (6) | [54-56,76] | |
| Muse | 3 (4) | [21,22,58] | |
| Others | 29 (42) | [23,24,28,29,39-41,44-46,49,51,53,57,58,60,61,64,67,72,74,77,79-83,85,87] | |
| Not reported | 5 (7) | [39,44,45,61,72] | |
| Company of WDb | |||
| Cambridge Neurotechnology | 17 (25) | [19,20,32,34-36,42,43,47,48,62,65,68-71,86] | |
| Fitbit Inc | 11 (16) | [25,26,30,31,33,38,50,52,59,63,73,80,84] | |
| Empatica Inc | 7 (10) | [27,37,58,66,75,78,85] | |
| YEI Technology | 4 (6) | [54-56,76] | |
| InteraXon | 3 (4) | [21,22,58] | |
| Philips | 3 (4) | [41,46,57] | |
| Others | 27 (39) | [23,24,28,29,39,40,44,45,49,51,53,57,58,60,61,64,67,72,74,77,79-83,85,87] | |
| Not applicable | 5 (7) | [39,44,45,61,72,82] | |
| Type of WDb | |||
| Smart band | 50 (72) | [21-26,28-31,33-40,42,44,45,47,50-59,61,63,66,69-76,78,79,81,84,85] | |
| Smartwatch | 16 (23) | [19,20,32,41,43,46,48,49,60,62,65,67,68,77,83,86] | |
| Others (smart shirt, smart adhesive electrodes, smart headset, smart glasses, smart ring, and smart shirt) | 5 (7) | [64,80,82,85,87] | |
| Placementb | |||
| Wrist | 57 (83) | [19,20,23-39,41-52,57-63,65-71,73-75,77-81,83-86] | |
| Head | 7 (10) | [21,22,53,54,58,76,87] | |
| Waist | 6 (9) | [28,54-56,72,76] | |
| Chest | 4 (6) | [58,80,82,85] | |
| Others (ankle, arm, eyes, finger, hand, neck, and thigh) | 1 (each) (1) | [27,39,40,64,87] | |
| Compatibility with OSc,d | |||
| Windows (Corp) | 52 (75) | [19-22,25-27,30-38,40-43,46-50,52,53,57-59,61-63,65-75,78,80,81,83-87] | |
| iOS (Apple Inc) | 36 (52) | [21-31,33,37,38,50-53,58-60,63,64,66,73-75,77-81,83-85,87] | |
| Android | 35 (51) | [21-23,25-28,30,31,33,37,38,40,50-53,58-60,63,64,66,73-75,77-81,83-85,87] | |
| Mac OS (Apple Inc) | 27 (39) | [21,22,25-27,30,31,33,37,38,50,52,53,58,59,63,66,67,73-75,78,80,81,84,85,87] | |
| Linux | 3 (4) | [21,22,58] | |
| Not reported | 8 (12) | [39,44,45,54-56,76,82] | |
| Gatewaye | |||
| Smartphone | 21 (30) | [23,25,26,29-31,33,38,40,50,52,59-61,63,64,73,79,80,83,84] | |
| PC | 13 (19) | [25,26,30,31,33,38,50,52,59,63,73,80,84] | |
| Tablet | 13 (19) | [25,26,30,31,33,38,50,52,59,63,73,80,84] | |
| Silmee L20 gateway | 1 (1) | [79] | |
| Not reported | 48 (70) | [19-22,24,27,28,32,34-37,39,41-49,51,53-58,62,65-72,74-78,81,82,85-87] | |
| Hostf | |||
| PC | 46 (67) | [19-22,27,28,32,34-37,39-49,53-58,62,65-72,74-78,81,85-87] | |
| Server | 30 (43) | [23,25-27,29-31,33,37,38,50,52,58-61,63,64,66,73-75,78-85] | |
| Smartphone | 16 (23) | [21,22,24,27,37,51,53,58,66,74,75,77,78,81,85,87] | |
| Tablet | 8 (12) | [21,22,53,58,74,77,81,87] | |
| Mode of data transferg | |||
| Bluetooth | 41 (59) | [21-27,29-31,33,37,38,40,50-56,58-61,63,64,66,73-81,83-85,87] | |
| Docking station | 27 (39) | [19,20,27,32,34-37,41-43,47-49,57,62,65-71,75,78,85,86] | |
| Internet | 24 (35) | [23,25,26,29-31,33,38,40,50,52,54-56,59,61,63,64,73,76,79,80,83,84] | |
| Removable media | 8 (12) | [39,44,45,54-56,76,82] | |
| Wired | 8 (12) | [28,46,54-56,58,72,76] | |
| ANT+ (ANT Wireless) | 1 (1) | [81] | |
aThe number of studies does not add up, as 1 (1%) study has both commercial and noncommercial wearable devices.
bThe number of studies does not add up, as several studies have used >1 wearable device.
cThe number of studies does not add up, as several studies have used >1 wearable device, and many wearable devices are compatible with >1 operating system.
dOS: operating system.
eThe number of studies does not add up, as several studies used >1 wearable device, and many wearable devices used >1 gateway.
fThe number of studies does not add up, as several studies used >1 wearable device, and many wearable devices used >1 host.
gThe number of studies does not add up, as several studies used >1 wearable device, and many wearable devices used >1 mode of data transfer.