Table 3.
Mean values of primary outcomes at baseline and follow-up after a diabetes prevention intervention
| Outcome variable | Group | Baselinea mean (SD) | 6 - monthsb mean (SD) | 12 monthsb mean (SD) | 18 monthsb mean (SD) | RM ANOVA Group × visit Interaction p-valuec | RM ANOVA Effect of visit p-valued |
|---|---|---|---|---|---|---|---|
| Total energy intake (kcal/day) | Intervention | 2201.3 (971.8) | 1921.5 (763.9) | 1846.2 (710.7) | 1883.3 (652.9) | 0.46 | <0.001 |
| Control | 2191.8 (978.2) | 1953.8 (795.5) | 1976.2 (855.9) | 1694.8 (876.4) | |||
| Total fat intake (g/day) | Intervention | 94.9 (44.5) | 82.4 (36.5) | 80.2 (35.4) | 81.0 (33.2) | 0.55 | <0.001 |
| Control | 96.6 (49.6) | 85.4 (41.9) | 87.8 (44.2) | 86.3 (44.6) | |||
| Saturated fat intake (g/day) | Intervention | 29.7 (14.2) | 25.7 (11.5) | 25.0 (10.9) | 24.9 (10.0) | 0.76 | <0.001 |
| Control | 30.0 (15.2) | 26.2 (12.6) | 26.4 (12.5) | 26.4 (13.5) | |||
| Vegetable intake (servings/day) | Intervention | 2.90 (1.71) | 3.21 (2.41) | 2.81 (1.67) | 3.17 (2.05) | 0.02 | — |
| Control | 2.73 (1.69) | 2.86 (1.96) | 2.68 (1.68) | 2.83 (1.96) | |||
| Total leisure- time activity (min/week) | Intervention | 5.06 (4.83) | 5.22 (4.56) | 5.08 (5.14) | 4.94 (4.89) | 0.48 | 0.30 |
| Control | 6.13 (6.40) | 5.67 (6.58) | 5.29 (4.93) | 5.22 (4.93) |
Baseline means statistically equivalent between groups (all p>0.30 per student t-test). n=96 for the Intervention group and n=95 for the Control group for all dietary variables; n=100 per group for total leisure-time activity.
Missing data due to dropping out of the study were addressed by applying intention to treat (last value carried forward). Remaining missing data were interpolated by averaging the adjacent values.
Repeated measures analyses of variance (RM ANOVA) model for each outcome variable with Group (Intervention versus Control) as a grouping variable, visit as a repeated factor and with group by visit interaction term.
If group by visit interaction was not significant, then additive RM ANOVA model with Group (Intervention versus Control) as a grouping variable and visit as the repeated variable.