Table 4.
Digital therapeutic components, decision support interventions, user retention and engagement, and attrition rates in the included studies (N=12).
| Study, duration | Digital therapeutic components | Recommended timing and frequency | Decision support interventions | Underlying BCTsa | User retention and engagement | Attrition rate,b % |
| Bailey et al [34], 12 weeks | 1. Sensor-guided exercise therapy: instructional videos and real-time graphics; 2. Remote personal health coaching and educational papers | Weekly 3 sessions of sensor-guided exercise therapy, 2 educational papers, 3 aerobic exercise activities, and 4 modules based on cognitive behavioral therapy | Peer-group interaction and support through in-app discussion feed; 20-30 participants who each used a discussion forum | Catastrophizing, active coping methods, fear avoidance, goal setting, and health tracking | Per week: Exercise therapy sessions: mean 2.9 (SD 1.46); education sessions: mean 2.2 (SD 1.55); interactions with coach: mean 7.0 (SD 3.09) | 27.71c |
| Priebe et al [28], 12 weeks | REd,e | RE | RE | RE | Physical exercise: mean 23 daysf; mindfulness: mean 15 days; education: mean 16 days | 27.20 |
| Hou et al [29], 24 months | 1. Rehabilitation video instructions; 2. Rehabilitation plans; 3. Communication with physicians through the app | Rehabilitation exercise: twice daily, with each session lasting 20 minutes | Daily rehabilitation exercise reports and alerts (prompting the user to return to the system) | Reminder | Highg: 62.29%; medium: 26.23%; low: 11.48% | 28.57 |
| Shebib et al [30], 12 weeks | 1. Sensor-guided exercise therapy; 2. Education, cognitive behavioral therapy, and behavioral coaching; 3. Activity and symptom tracking | Weekly 3 sessions of exercise therapy, 3 aerobic activities, 1-2 educational articles, and cognitive behavioral therapy on a subset of weeks | Peer-group interaction and coach support through in-app discussion feed, checklists, and point goals; weekly | Reminder, peer support, and gamification | Users engaging with the program per week: 75%; total number of workouts: mean 35.7 (SD 28.9); educational articles: mean 7.4 (SD 4.4); cognitive behavioral therapy session: mean 1.4 (SD 1.2) | 24.2 |
| Toelle et al [31], 12 weeks | 1. Physiotherapy and physical exercise; 2. Back pain–specific education; 3. Mindfulness and relaxation | Daily content consists of components 1-3; recommended use 4 times per week; up to 5 exercises per day | Customizable reminders, push notifications, health coach (chat function) | Reminder and motivation | Kaia app was used on mean 35 daysf (SD 22) | 20.07 |
| Chhabra et al [32], 12 weeks | 1. Tailored home exercise program, including back and aerobic exercises; 2. Activity and health plan | Daily: 4-km walk at a single stretch and 2 sets of 7 back exercises | Daily notifications and reminders; rewards system: points for each milestone achieved and access to the next level once enough points were collected | Gamification and reminder | NRh | 2.15 |
| Almhdawi et al [33], 6 weeks | 1. Set of stretching and evidence-based strengthening exercises; 2. Educational short posts modified from the Back Book | Weekly 3-4 sessions, each session lasting 20 minutes | Daily notifications (sound, vibration, and pop-up screen): 1. Reminder to take a walk break; 2. Reminder of the right posture; 3. Reminder of the stretching exercises; 4. Reminder of the home-based exercises | Reminder | NR | 4.88 |
| Lo et al [38], inconsistent | 1. Physical exercise program; 2. Educational material pushed to users through a social media platform | Recommended exercise duration: 20-30 minutes per day | Points-based rewards system to promote engagement with the app; reminder functions (daily) | Gamification and reminder | Time spent on exercises: mean 25 (SD 4) minutes per day; time spent on reading educational materials: mean 15 minutes per day (SD 14) | NR |
| Huber et al [35], 12 weeks | 1. Physiotherapy and physical exercise; 2. Back pain–specific education; 3. Mindfulness and relaxation techniques | Daily content consists of components 1-3, up to 5 exercises per day | Chat function connects user with a coach to receive motivation and help | Motivation | NR | 82.2 |
| Clement et al [36], 24 weeks | REe; additional component (4): Increased pool of each of the different exercise types (subdivided into 19 different difficulty levels in version 1.4 instead of 3 levels) | RE | RE | RE | Physical exercises: V1i: mean 1.99 (SD 1.61); V2i: mean 3.15 (SD 1.72); mindfulness exercises: V1: mean 1.36 (SD 1.43); V2: mean 2.42 (SD 1.82); educational content: V1: mean 1.51 (SD 1.42); V2: mean 2.71 (SD 1.89) | 64.9 |
| Priebe et al [37], 12 weeks | 1. Physiotherapy and physical exercise; 2. Back pain–specific education; 3. Mindfulness and relaxation techniques | Daily content consists of components 1-3, up to 5 exercises per day | Feedback (smileys and congratulatory messages) for achieving improvements, health coach (chat function), and push-up reminderse | Motivation and reminders | Mean number of days the app was used: V1: mean 22.11 daysf,j (SD 10.56); V2: mean 30.92 days (SD 32.27) | V1: 82; V2: 62 |
| Sandal et al [39], 6 weeks | 1. General physical activity; 2. Strength and flexibility exercises; 3. Patient education (access to variety of tools and information for low back pain) | Daily goal: 10,000 steps; 4 weekly exercise sessions; 1 reading task on education | Weekly tailored self-management plans: 1. Suggest activity goals; 2. Suggest a new exercise program; 3. Suggest new education sessions | Multiple BCTs | After 6 weeks; mean values 65 app visits (range 1-188); 134 minutes spent on the app (range 0-889); visited the app on 22 of the 42 possible days (range 1-42) | 13.72 |
aBCT: behavior change technique.
bAt final follow-up measurement of the intervention group.
cDefined as completing at least one exercise session or reading 1 educational paper in weeks 9-12.
eInvolves studies including the Kaia app; all information on the type of therapeutic components and applied interventions was extracted as described within the respective publication.
fNumber of days within the whole intervention length.
gThose who completed ≥5 training sessions each week were considered high adherence, 3-5 training sessions medium adherence, and ≤2 training sessions low adherence.
hNR: Not reported.
iComparison between 2 subsequent app versions: version 0.x (V1) and version 1.x (V2). V1 includes users who signed in before May 1, 2017, and V2 includes users who signed in after that date.
jA day was classified as an active day when the user logged into the app and completed at least one module.