Table 3. Means, s.d.s, percentage change and effect sizes (Cohen’s d) for the primary and secondary outcome measures.
| Estimated marginal means (s.d.) | Percentage change from assessment (95% CI)a | Within group effect size from assessment (95% CI) | Between group effect size at post-treatment (95% CI) | Between group effect size at 3-month follow-up (95% CI) | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| n | Assessment | Post-treatment | 3-month follow-up | Post-treatment | 3-month follow-up | Post-treatment | 3-month follow-up | Clinician-guided | Self-guided with assessment | Purely self-guided | Clinician guided | Self-guided with assessment | Pure Self-guided | |
| Primary outcomes | ||||||||||||||
| Depression (PHQ-9) | ||||||||||||||
| iCG | 153 | 10.74 (4.88) |
4.39 (3.81) |
4.30 (3.37) |
59 (53 to 64) |
60 (55 to 65) |
1.45 (1.20–1.70) |
1.54 (1.28–1.79) |
– | −0.01 (−0.24 to 0.22) |
−0.10 (−0.33 to 0.13) |
– | −0.11 (−0.34 to 0.12) |
−0.13 (−0.35 to 0.10) |
| iSG | 140 | 10.43 (4.61) |
4.44 (3.67) |
4.71 (3.79) |
57 (51 to 63) |
55 (48 to 60) |
1.44 (1.17–1.70) |
1.36 (1.09–1.61) |
– | – | −0.09 (−0.32 to 0.14) |
– | – | −0.01 (−0.24 to 0.22) |
| SG | 140 | 10.43 (4.73) |
4.78 (3.90) |
4.75 (3.79) |
54 (48 to 60) |
54 (48 to 60) |
1.30 (1.04–1.56) |
1.33 (1.06–1.58) |
– | – | – | – | – | – |
| Anxiety (GAD-7) | ||||||||||||||
| iCG | 153 | 9.86 (4.58) |
4.17 (3.96) |
3.73 (3.09) |
58 (51 to 64) |
62 (57 to 67) |
1.33 (1.08–1.57) |
1.57 (1.31–1.82) |
– | −0.14 (−0.37 to 0.09) |
−0.26 (−0.49 to −0.02) |
– | −0.41 (−0.41 to 0.05) |
−0.22 (−0.45 to −0.01) |
| iSG | 140 | 10.45 (4.38) |
4.74 (4.02) |
4.36 (3.90) |
55 (48 to 61) |
58 (52 to 64) |
1.36 (1.09–1.61) |
1.47 (1.20–1.73) |
– | – | −0.11 (−0.35 to 0.12) |
– | – | −0.04 (−0.27 to 0.20) |
| SG | 140 | 10.44 (4.14) |
5.19 (4.02) |
4.50 (3.79) |
50 (43 to 56) |
57 (51 to 62) |
1.29 (1.03–1.54) |
1.50 (1.23–1.76) |
– | – | – | – | – | – |
| Secondary outcomes | ||||||||||||||
| Geriatric depression (GDS) | ||||||||||||||
| iCG | 153 | 8.07 (3.46) |
4.83 (3.71) |
4.41 (3.59) |
40 (32 to 47) |
45 (38 to 52) |
0.90 (0.67–1.14) |
1.04 (0.80–1.28) |
– | 0.03 (−0.20 to 0.26) |
−0.15 (−0.38 to 0.08) |
– | 0.02 (−0.21 to 0.25) |
−0.02 (−0.25 to 0.20) |
| iSG | 140 | 7.82 (3.79) |
4.73 (3.43) |
4.35 (3.55) |
40 (32 to 46) |
44 (36 to 51) |
0.85 (0.61–1.10) |
0.94 (0.70–1.19) |
– | – | −0.18 (−0.42 to 0.05) |
– | – | −0.04 (−0.28 to 0.19) |
| SG | 140 | 7.72 (3.59) |
5.36 (3.43) |
4.50 (3.67) |
31 (23 to 38) |
42 (33 to 49) |
0.67 (0.43–0.91) |
0.89 (0.64–1.13) |
– | – | – | – | – | – |
| Psychological distress (K-10) | ||||||||||||||
| iCG | 153 | 24.92 (6.68) |
17.01 (6.31) |
16.05 (5.57) |
32 (28 to 36) |
36 (32 to 39) |
1.22 (0.97–1.46) |
1.44 (1.19–1.69) |
– | −0.11 (−0.34 to 0.12) |
−0.23 (−0.46 to 0.00) |
– | −0.12 (−0.35 to 0.11) |
−0.19 (−0.42 to 0.04) |
| iSG | 140 | 24.97 (6.51) |
17.69 (5.92) |
16.76 (5.92) |
29 (25 to 33) |
33 (29 to 37) |
1.17 (0.91–1.42) |
1.32 (1.06–1.57) |
– | – | −0.13 (−0.37 to 0.10) |
– | – | −0.07 (−0.31 to 0.16) |
| SG | 140 | 25.09 (6.15) |
18.50 (6.39) |
17.21 (6.39) |
26 (22 to 30) |
31 (27 to 36) |
1.05 (0.80–1.30) |
1.26 (1.00–1.51) |
– | – | – | – | – | – |
| Tertiary outcomes | ||||||||||||||
| Disability (SDS) | ||||||||||||||
| iCG | 153 | 11.51 (7.79) |
6.17 (6.06) |
5.53 (6.56) |
46 (37 to 54) |
52 (42 to 60) |
0.77 (0.53–1.00) |
0.83 (0.59–1.06) |
– | −0.02 (−0.25 to 0.21) |
−0.06 (−0.29 to 0.17) |
– | −0.03 (−0.26 to 0.19) |
−0.00 (−0.23 to 0.23) |
| iSG | 140 | 11.47 (7.22) |
6.31 (6.63) |
5.76 (6.74) |
45 (35 to 54) |
50 (39 to 59) |
0.74 (0.50–0.98) |
0.82 (0.57–1.06) |
– | – | −0.04 (−0.27 to 0.20) |
– | – | −0.03 (−0.20 to 0.27) |
| SG | 140 | 10.94 (6.98) |
6.54 (6.15) |
5.54 (6.27) |
40 (30 to 49) |
49 (39 to 58) |
0.67 (0.43–0.91) |
0.81 (0.57–1.06) |
– | – | – | – | – | – |
| Life satisfaction (SWLS) | ||||||||||||||
| iCG | 153 | 16.38 (6.93) |
19.63 (7.92) |
20.89 (7.79) |
−20 (−28 to −12) |
−28 (−35 to −20) |
0.44 (0.21–0.66) |
0.61 (0.38–0.84) |
– | −0.11 (−0.34 to 0.12) |
−0.03 (−0.26 to 0.20) |
– | −0.00 (−0.23 to 0.23) |
−0.05 (−0.28 to 0.17) |
| iSG | 140 | 16.52 (6.98) |
20.46 (7.22) |
20.92 (7.69) |
−24 (−31 to −17) |
−27 (−35 to −19) |
0.55 (0.31–0.79) |
0.60 (0.36–0.84) |
– | – | 0.08 (−0.16 to 0.31) |
– | – | −0.05 (−0.29 to 0.18) |
| SG | 140 | 17.94 (7.22) |
19.88 (7.57) |
21.32 (7.93) |
−11 (−18 to −4) |
−19 (−26 to −12) |
0.26 (0.03–0.50) |
0.45 (0.21–0.68) |
– | – | – | – | – | – |
iCG, interview plus clinician-guided internet-delivered cognitive–behavioural therapy (iCBT); iSG, interview plus self-guided iCBT; SG, self-guided iCBT; GAD-7, Generalised Anxiety Disorder 7-item scale; PHQ-9, 9-item Patient Health Questionnaire; GDS-15, 15-item Geriatric Depression Scale; K-10, 10-item Kessler Psychological Distress Scale; SDS, Sheehan Disability Scale; SWLS, Satisfaction with Life Scale.
a
The percentage change from baseline statistics are estimates of relative change derived from the GEE models conducted separately for each outcome.