Table 2.
Effects of internet-delivered cognitive behavioral therapy for insomnia group compared with the control group on primary and secondary outcomes.
| Outcome | Internet-delivered cognitive behavioral therapy for insomnia group, mean (SE) | Control group, mean (SE) | Mean difference between groups (95% CI) | P value | Cohen d (95% CI) | Group × time, P value | |||
| Primary outcome | |||||||||
|
|
Insomnia Severity Index | <.001 | |||||||
|
|
|
T1a | 16.35 (0.46) | 16.32 (0.46) | N/Ab | N/A | N/A |
|
|
|
|
|
T2c | 10.03 (0.48) | 14.40 (0.48) | −4.36 (−5.69 to −3.03) | <.001 | 0.97 (0.66 to 1.28) |
|
|
|
|
|
T3d | 10.30 (0.45) | 13.93 (0.45) | −3.64 (−4.89 to −2.39) | <.001 | 0.86 (0.55 to 1.17) |
|
|
| Mental health | |||||||||
|
|
Center for Epidemiological Studies-Depression Scale | <.001 | |||||||
|
|
|
T1 | 22.08 (0.89) | 20.78 (0.88) | N/A | N/A | N/A |
|
|
|
|
|
T2 | 15.40 (0.88) | 17.91 (0.88) | −2.52 (−4.97 to −0.06) | .044 | 0.30 (0.01 to 0.60) |
|
|
|
|
|
T3 | 16.75 (0.83) | 20.30 (0.82) | −3.55 (−5.86 to −1.24) | .003 | 0.46 (0.16 to 0.76) |
|
|
|
|
Recuperation in Sleep subscalee | <.001 | |||||||
|
|
|
T1 | 2.35 (0.06) | 2.43 (0.06) | N/A | N/A | N/A |
|
|
|
|
|
T2 | 3.01 (0.07) | 2.50 (0.07) | 0.51 (0.31 to 0.70) | <.001 | 0.78 (0.47 to 1.08) |
|
|
|
|
|
T3 | 3.11 (0.06) | 2.58 (0.06) | 0.53 (0.35 to 0.71) | <.001 | 0.94 (0.63 to 1.25) |
|
|
| Work-related health | |||||||||
|
|
Recreation Experience and Activity Questionnairee | .121 | |||||||
|
|
|
T1 | 47.07 (1.02) | 45.11 (1.01) | N/A | N/A | N/A |
|
|
|
|
|
T2 | 51.4 (1.05) | 46.65 (1.04) | 4.75 (1.83 to 7.68) | .002 | 0.48 (0.18 to 078) |
|
|
|
|
|
T3 | 51.10 (1.00) | 47.12 (0.99) | 3.98 (1.21 to 6.75) | .005 | 0.43 (0.13 to 0.72) |
|
|
|
|
Work Ability Indexe | .006 | |||||||
|
|
|
T1 | 6.88 (0.18) | 6.94 (0.17) | N/A | N/A | N/A |
|
|
|
|
|
T3 | 7.14 (0.20) | 6.46 (0.20) | 0.68 (0.12 to 1.22) | .017 | 0.51 (0.21 to 0.81) |
|
|
|
|
Absenteeismf | .869 | |||||||
|
|
|
T1 | 4.62 (0.95) | 2.69 (0.94) | N/A | N/A | N/A |
|
|
|
|
|
T3 | 4.71 (1.14) | 3.14 (1.14) | 1.57 (−1.61 to 4.75) | .333 | 0.21 (−0.09 to 0.50) |
|
|
|
|
Presenteeismf | .103 | |||||||
|
|
|
T1 | 10.69 (1.43) | 13.17 (1.42) | N/A | N/A | N/A |
|
|
|
|
|
T3 | 5.94 (1.18) | 12.39 (1.17) | −6.455 (−9.73 to 3.18) | <.001 | 0.83 (0.52 to 1.13) |
|
|
| Cognitive activity | |||||||||
|
|
Cognitive irritation subscale | <.001 | |||||||
|
|
|
T1 | 15.52 (0.37) | 15.79 (0.36) | N/A | N/A | N/A |
|
|
|
|
|
T2 | 11.18 (0.40) | 14.43 (0.39) | −3.25 (−4.35 to −2.15) | <.001 | 0.87 (0.57 to 1.18) |
|
|
|
|
|
T3 | 12.20 (0.39) | 15.19 (0.39) | −2.99 (−4.08 to −1.90) | <.001 | 0.81 (0.51 to 1.12) |
|
|
|
|
Penn State Worry Questionnaire Past Week | <.001 | |||||||
|
|
|
T1 | 9.21 (0.41) | 8.23 (0.41) | N/A | N/A | N/A |
|
|
|
|
|
T2 | 5.77 (0.40) | 6.85 (0.39) | −1.08 (−2.18 to 0.02) | .05 | 0.29 (−0.01 to 0.59) |
|
|
|
|
|
T3 | 6.9 (0.39) | 8.35 (0.39) | −1.46 (−2.55 to −0.36) | .009 | 0.39 (0.10 to 0.69) |
|
|
aAt baseline.
bNot applicable.
cPostintervention (8 weeks postrandomization).
dAt 6-month follow-up (4 months postintervention).
eHigher scores indicate better outcome.
fIn relation to the previous 3 months.