Table 2.
Adjusted Means and Changes Scores on the Primary Outcome (Insomnia Severity Index) According to Group and Time
| Means (standard errors), by time and change scores | Comparison between groups |
|||||
|---|---|---|---|---|---|---|
| Time (or change) | CBT | CT | BT | Effect | F(2,323)a | Post-hoca |
| Insomnia Severity Index (ISI) | ||||||
| t1 (Pre) | 18.51 (0.49) | 18.16 (0.48) | 18.91 (0.43) | cond/t1 | 0.88, p = .42 | |
| t2 (Post) | 7.94 (0.58) | 9.95 (0.63) | 9.57 (0.69) | cond/t2 | 3.71, p = .03 (.03) | CBT<CT |
| t3 (FU6) | 8.10 (0.62) | 9.25 (0.76) | 10.16 (0.73) | cond/t3 | 2.73, p = .07 | |
| Change t1-t2 (ES) | −10.56***(−2.50) | −8.21*** (−1.94) | −9.34*** (−2.21) | cond/t1-t2 | 3.39, p = .05 (.04) | CBT>CT |
| Change t1-t3 (ES) | −10.40***(−2.46) | −8.91*** (−2.11) | −8.75*** (−2.07) | cond/t1-t3 | 1.91, p = .15 | |
| Change t2-t3 (ES) | 0.16 NS (0.04) | −0.69 NS (−0.16) | 0.59 NS (0.14) | cond/t2-t3 | 1.08, p = .34 | |
| ISI Response - % (reduction of at least 8 points from baseline) | ||||||
| t1 (Pre) | ||||||
| t2 (Post) | 67.25 (6.99) | 42.42 (6.65) | 67.35 (7.00) | cond/t2 | 4.84, p = .01 (.02) | CBT=BT>CT |
| t3 (FU6) | 67.55 (6.98) | 62.59 (7.12) | 44.44 (7.74) | cond/t3 | 2.94, p = .06 | |
| Change t2-t3 | 0.30 NS | 20.17 *** | −22.91 *** | cond/t2-t3 | 10.07, p = .00 (.00) | CT>CBT>BT |
| ISI Remission - % (ISI < 8) | ||||||
| t1 (Pre) | ||||||
| t2 (Post) | 57.29 (7.40) | 30.84 (6.33) | 39.37 (6.78) | cond/t2 | 3.81, p =.02 (.02) | CBT>CT |
| t3 (FU6) | 55.82 (7.29) | 51.62 (7.34) | 36.45 (7.08) | cond/t3 | 2.21, p = .11 | |
| Change t2-t3 | −1.47 NS | 20.78 ** | −2.92 NS | cond/t2-t3 | 3.86, p = .02 (.02) | CT>CBT=BT |
*
p < .05
**
p < .01
***
p < .001
Note. All means (standard errors) and change scores are adjusted for site and stratification effects.
a
p-values in parentheses are corrected for multiplicity. df = 2,153 for ISI Response and Remission. ES = effect size (Cohen’s d) for change scores.