Table 3.
Treatment Engagement
| Variable | Internet-only | Internet + incentives | p-value |
|---|---|---|---|
| Weeks 1‒8 (Months 1‒2) | |||
| Attendance | |||
| Number weekly group chat sessions attended (out of 8), M±SD | 6.7± 1.9 | 7.4 ± 1.2 | 0.0007 |
| Proportion attending ≥75% of weekly group chat sessions | 85% | 93% | 0.007 |
| Self-monitoring | |||
| Number of days with body weight self-reported (out of 56), M±SDa | 32 ± 17 | 49 ± 10 | <0.0001 |
| Proportion recording body weight ≥50% of days (i.e., ≥28 days) | 61% | 95% | <0.0001 |
| Dietary intake, days reported recording (out of 56), M±SDa | 36 ± 17 | 50 ± 10 | <0.0001 |
| Proportion reporting recorded dietary intake ≥50% days (i.e., ≥28 days) | 72% | 96% | <0.0001 |
| Physical activity, days reported (out of 56), M±SD | 37 ± 17 | 50 ± 10 | <0.0001 |
| Proportion reporting physical activity ≥50% days (i.e., ≥28 days) | 75% | 96% | <0.0001 |
| Self-reported goal attainmentc | |||
| Number of weeks met goal of ≥200 minutes/week of MVPA (max 8; M±SD) | 1.8 ± 2.3 | 3.3 ± 2.9 | <0.0001 |
| Number days met goal of ≥10,000 steps/day (max 56; M±SD) | 9.2 ± 11.8 | 15.1 ± 14.7 | <0.0001 |
| Number of days met calorie goal (max 56; M±SD) | 24 ± 15 | 36 ± 13 | <0.0001 |
| Self-reported physical activityd | |||
| Minutes/week on days when minutes reported, M±SD | 132 ± 98 | 200 ± 127 | <0.0001 |
| Number steps/day on days when steps reported, M±SD | 7,071 ± 2,813 | 7,806 ± 2,659 | 0.01 |
| Weeks 9‒24 (Months 3‒6) | |||
| Attendance | |||
| Number weekly group chat sessions attended (out of 16), M±SD | 9.1 ± 5.2 | 11.2 ± 4.4 | 0.0005 |
| Proportion attending ≥75% of weekly group chat sessions | 46% | 62% | 0.0151 |
| Self-monitoring | |||
| Number of days with body weight self-reported (out of 112), M±SDb | 40 ± 36 | 66 ± 37 | <0.0001 |
| Proportion recording body weight ≥50% of days (i.e., ≥56 days) | 35% | 63% | <0.0001 |
| Dietary intake, days reported recording (out of 112), M±SDb | 44 ± 30 | 66 ± 38 | <0.0001 |
| Proportion reporting recorded dietary intake ≥50% days (i.e., ≥56 days) | 39% | 49% | 0.0006 |
| Physical activity, days reported (out of 112), M±SD | 47 ± 39 | 68 ± 38 | <0.0001 |
| Proportion reporting physical activity ≥50% days (i.e., ≥56 days) | 42% | 63% | 0.0008 |
| Self-reported goal attainmentc | |||
| Number of weeks met goal of ≥200 minutes/week of MVPA (max 16; MSD) | 3.0 ±4.6 | 5.5 ± 5.8 | <0.0001 |
| Number days met goal of ≥10,000 steps/day (max 112; M±SD) | 18.3 ± 26.2 | 27.0 ± 29.3 | 0.0004 |
| Number of days met calorie goal (max 112; M±SD)d | 33 ± 32 | 48 ± 33 | <0.0001 |
| Self-reported physical activityd | |||
| Minutes/week on days when minutes reported, M±SD | 133 ± 99 | 191 ± 148 | 0.003 |
| Number steps/day on days when steps reported, M±SD | 8,174 ± 3,134 | 8,386 ± 2,769 | 0.44 |
| Month 1‒Month 6 | |||
| Attendance | |||
| Number weekly group chat sessions attended (out of 24), M±SD | 16 ± 6.6 | 18 ± 5.1 | <0.0001 |
| Proportion attending ≥75% of weekly group chat sessions | 51% | 70% | 0.002 |
| Self-monitoring | |||
| Number of days with body weight self-reported (out of 168), M±SDa | 72 ± 51 | 115 ± 43 | <0.0001 |
| Proportion recording body weight ≥50% of days (i.e., ≥84 days) | 42% | 74% | <0.0001 |
| Dietary intake, days reported recording (out of 168), M±SDa | 85 ± 54 | 119 ± 44 | <0.0001 |
| Proportion reporting recorded dietary intake ≥50% days (i.e., ≥84 days) | 49% | 76% | <0.0001 |
| Physical activity, days reported (out of 168), M±SD | 85 ± 54 | 118 ± 44 | <0.0001 |
| Proportion self-monitoring physical activity ≥50% days (i.e., ≥84 days) | 49% | 75% | <0.0001 |
| Self-reported goal attainmentc | |||
| Number of weeks met goal of ≥200 minutes/week of MVPA (max 24; M±SD) | 5 ± 6 | 9 ± 8 | <0.0001 |
| Number days met goal of ≥10,000 steps/day (max 168; M±SD) | 27 ± 36 | 42 ± 41 | 0.0003 |
| Number of days met calorie goal (max 168; M±SD)d | 56 ± 44 | 83 ± 42 | <0.0001 |
| Self-reported physical activityd | |||
| Minutes/week on days when minutes reported, M±SD | 127 ± 91 | 193 ± 131 | <0.0001 |
| Number steps/day on days when steps reported, M±SD | 7,447 ± 2,888 | 8,057± 2,672 | 0.04 |
Notes: Boldface indicates statistical significance (p<0.05).
a
Incentivized during Weeks 1‒8 in the Internet + incentives condition.
b
No longer incentivized during Weeks 9‒24.
c
If no self-report of adherence to calorie, step or minutes physical activity goal was provided on a given day, it was assumed that the goal was not met on that day.
d
Includes reported data only (no imputed data).
MVPA, moderate-to-vigorous physical activity.