Table 3.
Estimated Coefficients of the Linear Mixed Models of the Primary Outcome Measures BDI and QIDS-C.19,20
| Estimate | SE | t Value | Significances | |
|---|---|---|---|---|
| BDI | ||||
| Intercept | 16.72 | 1.01 | 16.63 | |
| Baseline score | 0.52 | 0.09 | 5.74 | |
| 1 year (T4) | 2.42 | 0.50 | 4.86 | F(2, 301.3) = 18.5, P ≤ 0.001a |
| 2 years (T6) | 0.06 | 0.53 | 0.12 | |
| 3 years (T8) | –2.48 | 0.53 | –4.70 | |
| PREF CBT | –0.68 | 1.29 | –0.53 | F(3, 198.3) = 0.68, p = 0.56b |
| PREF PAT | 1.54 | 1.06 | 1.45 | |
| RAND CBT | –0.27 | 1.38 | –0.20 | |
| RAND PAT | –0.58 | 1.32 | –0.44 | |
| No medication T0 | –1.14 | 1.14 | –1.00 | |
| Medication T0 | 2.78 | 1.15 | 2.41 | |
| Missing medication T0 | –1.64 | 1.77 | –0.93 | |
| PREF CBT T4 | –1.14 | 0.91 | –1.26 | F(6, 296.2) = 0.88, p = 0.51c |
| PREF PAT T4 | 0.46 | 0.71 | 0.65 | |
| RAND CBT T4 | –0.18 | 0.90 | –0.20 | |
| RAND PAT T4 | 0.86 | 0.91 | 0.94 | |
| PREF CBT T6 | –0.84 | 0.96 | –0.88 | |
| PREF PAT T6 | –0.36 | 0.76 | –0.48 | |
| RAND CBT T6 | 1.02 | 0.96 | 1.06 | |
| RAND PAT T6 | 0.19 | 0.95 | 0.20 | |
| PREF CBT T8 | 1.98 | 0.97 | 2.04 | |
| PREF PAT T8 | –0.10 | 0.76 | –0.13 | |
| RAND CBT T8 | –0.84 | 0.93 | –0.89 | |
| RAND PAT T8 | –1.05 | 0.98 | –1.07 | |
| QIDS-C | ||||
| Intercept | 6.81 | 0.39 | 17.68 | |
| Baseline score | 0.50 | 0.09 | 5.33 | |
| 1 year (T4) | 1.07 | 0.22 | 4.92 | F(2, 326.5) = 16.3, P ≤ 0.001a |
| 2 years (T6) | –0.12 | 0.22 | –0.53 | |
| 3 years (T8) | –0.95 | 0.22 | –4.24 | |
| PREF CBT | 0.19 | 0.49 | 0.38 | F(3, 203.8) = 0.62, p = 0.60b |
| PREF PAT | 0.56 | 0.42 | 1.34 | |
| RAND CBT | –0.43 | 0.54 | –0.79 | |
| RAND PAT | –0.32 | 0.53 | –0.60 | |
| No medication T0 | –0.91 | 0.44 | –2.09 | |
| Medication T0 | 0.37 | 0.45 | 0.82 | |
| Missing medication T0 | 0.54 | 0.67 | 0.80 | |
| PREF CBT T4 | –1.17 | 0.39 | –2.97 | F(6, 318.4) = 3.67, p = 0.0015c |
| PREF PAT T4 | 0.37 | 0.32 | 1.17 | |
| RAND CBT T4 | 0.04 | 0.40 | 0.09 | |
| RAND PAT T4 | 0.76 | 0.39 | 1.95 | |
| PREF CBT T6 | –0.34 | 0.39 | –0.86 | |
| PREF PAT T6 | –0.52 | 0.32 | –1.59 | |
| RAND CBT T6 | 1.02 | 0.42 | 2.45 | |
| RAND PAT T6 | –0.16 | 0.40 | –0.41 | |
| PREF CBT T8 | 1.51 | 0.41 | 3.71 | |
| PREF PAT T8 | 0.14 | 0.32 | 0.45 | |
| RAND CBT T8 | –1.06 | 0.40 | –2.63 | |
| RAND PAT T8 | –0.59 | 0.42 | –1.42 |
BDI, Beck Depression Inventory II; CBT, cognitive-behavioural therapy; PAT, psychoanalytic therapy; PREF, preference arm; QIDS-C, clinician-rated Quick Inventory of Depressive Symptoms; RAND, randomization arm. Shown are the estimated coefficients of the additive mixed models with the dependent variables BDI-II and QIDS-C scores, the estimated standard errors, t values, and the significance of approximate F tests of a model, including the corresponding covariate/parameters against the smaller nested model. The model includes the baseline score as a continuous covariate, time, treatment group, medication, and the interaction between time and treatment. Effect coding has been used, so the coefficients of time and treatment group indicate differences from the overall mean on the respective outcome scales. Estimated random intercept standard deviations were 8.5 (BDI-II) and 3.3 (QIDS-C); residual standard deviations were 7.2 (BDI-II) and 3.2 (QIDS-C).
a Refers to the effect of time.
b Refers the effect of therapy group.
c Refers to the interaction of time and treatment group.