Table 2.
Intervention engagement.
| Study | Total intervention length | Frequency of use, mean (SD) or median (IQR) | Intervention duration (min), mean (SD) or median (IQR) |
| Freeman et al, 2018 [23] | 6 × 30-min sessions over 2 weeks | 4.66 (SD 1.27) | 124.4 (SD 34.2) |
| Bird et al, 2018 [24] | 1 session | Not applicable | 13 (SD NRa) |
| Fulmer et al, 2018 [26] | Unlimited access for 2 weeks or 4 weeks | 192 interactions (SD NR) | NR |
| Fitzpatrick et al, 2017 [25] | Daily intervention for 2 weeks | 12.1 (SD 2.23) | NR |
| Ly et al, 2017 [33] | Daily intervention for 2 weeks | 17.71 | NR |
| Gaffney et al, 2014 [27] | 1 session | Not applicable | 19.23 (SD 0.002) |
| Inkster et al, 2018 [29] | Unlimited access for 2 weeks | 83% (90/108) of high-usage users (at least one use) used the app for more than 4 days | NR |
| Gardiner et al, 2017 [32] | Unlimited access for 30 days | NR | 52 (IQR 101.4) |
| Pinto et al, 2016 [30] | 3 × 15-20-min sessions (baseline, 4 weeks, and 8 weeks) | 12 of 25 participants completed all sessions | NR |
| Burton et al, 2016 [28] | Daily intervention over 4 weeks | 10.5 (IQR NR) | 134 (IQR NR) |
| Suganuma et al, 2018 [34] | At least 15 times over 1 month | 45% (191/427) completed >15 days of intervention | NR |
| Pinto et al, 2013 [31] | 3 sessions (baseline, 4 weeks, and 8 weeks) | NR | NR |
| Ring et al, 2015 [22] | Unlimited access over 1 week | 15.9 (SD 8.1) interactions | 2.3 (SD 0.038) each |
aNR: not reported.