Table 2

Analysis of main effects using the mixed-model L repeated measures analysis

ComponentN*Estimated least squares mean change scores of the PHQ-9†Estimated differences of change scores
(95% CI)
Effect size for Baseline-Week eight change scores‡
(95% CI)
Effect size for differences of change scores and their p values‡
(95% CI)
P value
Week 1Week 2Week 3Week 4Week 5Week 6Week 7Week 8
SM
 Presence544−0.79−1.31−1.50−1.86−1.70−1.75−1.79−1.880.19 (−0.29 to 0.67)−0.65 (−0.78 to -0.53)0.05 (−0.07 to 0.16)0.44
 Absence549−1.08−1.34−1.41−1.48−1.51−1.67−1.86−2.07−0.78 (−0.92 to -0.65)
BA
 Presence552−0.85−1.33−1.42−1.64−1.60−1.79−1.85−2.06−0.17 (−0.65 to 0.31)−0.73 (−0.86 to -0.60)−0.04 (−0.16 to 0.08)0.50
 Absence541−1.01−1.31−1.49−1.70−1.61−1.63−1.79−1.90−0.70 (−0.84 to -0.57)
CR
 Presence544−0.94−1.05−1.40−1.60−1.40−1.47−1.83−2.02−0.08 (−0.56 to 0.40)−0.75 (−0.89 to -0.62)−0.02 (−0.14 to 0.10)0.74
 Absence549−0.93−1.60−1.52−1.74−1.82−1.95−1.82−1.94−0.68 (−0.81 to -0.56)
AT
 Presence547−0.75−1.31−1.30−1.56−1.71−1.61−1.73−1.850.25 (−0.23 to 0.73)−0.67 (−0.80 to -0.54)0.06 (−0.06 to 0.18)0.31
 Absence546−1.12−1.34−1.62−1.78−1.50−1.81−1.91−2.10−0.76 (−0.89 to -0.63)
PS
 Presence546−0.80−1.38−1.48−1.63−1.63−1.74−1.86−1.910.14 (−0.34 to 0.62)−0.71 (−0.84 to -0.57)0.03 (−0.08 to 0.15)0.56
 Absence547−1.07−1.27−1.44−1.71−1.58−1.69−1.79−2.05−0.72 (−0.86 to −0.60)
  • *In a factorial trial design, all 1093 participants included in the analysis were randomly assigned 1:1 to either presence or absence of each component.

  • †Minus value indicates depression reduction.

  • ‡We calculated effect sizes (standardised mean differences) using the baseline SD for within-group change score and the week 8 SD for group differences.

  • AT, assertion training; BA, behavioural activation; CIDI, Composite International Diagnostic Interview; CR, cognitive restructuring; PHQ-9, Patient Health Questionnaire-9; PS, problem-solving; SM, self-monitoring