Table 2. Lagged Multilevel Moderated Mediation Analysis.
| c | a | b | c′ | ab | ||
|---|---|---|---|---|---|---|
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| Treatment | Change in Y | Change in M | M→Y controlling for time | Change in Y controlling for M | Indirect effect [95% CI] | Percent mediation (%) |
| Model 1: time → negative cognitions (M) → PTSD (Y) | ||||||
| PE + NAL | -2.33*** | -8.22***a | 0.09*** | -1.60*** | -0.73 [-0.32, -1.21] | 31.5 |
| PE + PBO | -2.56*** | -5.65***a | 0.10*** | -1.97*** | -0.59 [-0.26, -0.99] | 22.9 |
| SC + NAL | -1.56*** | -5.42***a | 0.09*** | -1.09** | -0.47 [-0.20, -0.82] | 30.1 |
| SC + PBO | -1.60*** | -1.77b | 0.10*** | -1.43*** | -0.17 [0.05, -0.45] | 10.8 |
| Reverse model:time → PTSD (M) → negative cognitions (Y) | ||||||
| PE + NAL | -6.58*** | -3.33***a | 1.06*** | -3.03 | -3.55 [-5.71, -1.55] | 53.9 |
| PE + PBO | -4.82** | -2.68***a | 0.92** | -2.36 | -2.46 [-4.36, -0.75] | 51.1 |
| SC + NAL | -4.04** | -1.97***b | 0.71* | -2.63 | -1.41 [-2.82, -0.17] | 34.9 |
| SC + PBO | -1.86 | -1.80***b | 0.52 | -0.91 | -0.94 [-2.27, 0.25] | 50.9 |
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| Model 2: time → craving (M) → drinking (Y) | ||||||
| PE + NAL | -2.30* | -2.06***a | 0.81** | -0.65 | -1.65 [-0.48, -2.92] | 71.7 |
| PE + PBO | -1.40 | -1.60*** | 0.75** | -0.20 | -1.21 [-0.38, -2.14] | 86.1 |
| SC + NAL | 0.96 | -1.39***b | 0.17 | 1.21a | -0.23 [0.49, -0.97] | — a |
| SC + PBO | -2.83*** | -1.48***b | 0.71** | -1.80**b | -1.01 [-0.25,-1.87] | 35.8 |
| Reverse model: time → drinking (M) → craving (Y) | ||||||
| PE + NAL | -0.87** | -8.44*** | 0.032 | -0.61* | -0.27 [-0.61, 0.06] | 30.6 |
| PE + PBO | -0.81** | -7.75*** | 0.034* | -0.55 | -0.26 [-0.51, -0.00] | 32.5 |
| SC + NAL | -0.75** | -7.23*** | 0.00 | -0.72** | -0.03 [-0.28, 0.21] | 4.1 |
| SC + PBO | -1.04*** | -8.22*** | 0.035 | -0.75** | -0.29 [-0.60, 0.01] | 27.8 |
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| Model 3a: time → PTSD (M) → craving (Y) | ||||||
| PE + NAL | -1.33*** | -3.33***a | 0.10 | -1.01*** | -0.33 [0.05, -0.72] | 24.5 |
| PE + PBO | -1.25*** | -2.68***a | 0.21*** | -0.67* | -0.57 [-0.25, -0.93] | 45.9 |
| SC + NAL | -0.97*** | -1.97***b | 0.07 | -0.83** | -0.14 [0.10, -0.41] | 14.8 |
| SC + PBO | -1.17*** | -1.80***b | 0.04 | -1.10*** | -0.07 [0.16, -0.31] | 5.8 |
| Reverse model: time → craving (M) → PTSD (Y) | ||||||
| PE + NAL | -2.48*** | -2.06***a | 0.35** | -1.74*** | -0.73 [-1.28, -0.23] | 29.5 |
| PE + PBO | -2.16*** | -1.60*** | 0.10 | -2.00*** | -0.16 [-0.48, 0.15] | 7.4 |
| SC + NAL | -1.73*** | -1.39***b | 0.15 | -1.52*** | -0.21 [-0.51, 0.06] | 12.1 |
| SC + PBO | -1.21** | -1.48***b | 0.07 | -1.11** | -0.10 [-0.43, 0.22] | 8.1 |
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| Model 3b: time → PTSD (M) → drinking (Y) | ||||||
| PE + NAL | -2.67* | -3.33***a | 0.39* | -1.38 | -1.29 [-0.08, -2.56] | 48.2 |
| PE + PBO | -1.57 | -2.68***a | 0.11 | -1.28 | -0.29 [0.72, -1.32] | 18.5 |
| SC + NAL | 0.31 | -1.95***b | 0.17 | 0.60a | -0.33 [0.44, -1.15] | — a |
| SC + PBO | -2.53** | -1.80***b | 0.25 | -2.08**b | -0.46 [0.25, -1.21] | 17.7 |
| Reverse model: time → drinking (M) → PTSD (Y) | ||||||
| PE + NAL | -1.96*** | -8.44*** | 0.036 | -1.65***a | -0.30 [-0.69, 0.73] | 15.4 |
| PE + PBO | -1.72*** | -7.75*** | 0.037a | -1.44** | -0.28 [-0.59, 0.01] | 16.5 |
| SC + NAL | -1.46*** | -7.23*** | -0.017b | -1.58***a | 0.12 [-0.14, 0.39] | — a |
| SC + PBO | -0.76 | -8.22*** | 0.042*a | -0.42b | -0.34 [-0.70, -0.01] | 45.1 |
Note. c, a, b, c′ represent the paths of the lagged mediation model as depicted in Figure 2. Bold type for ab (indirect effect) column indicates p < .05. Y = outcome variable; M = mediator; 95% CI = 95 percent confidence interval. Superscripts a and b denote significant difference between two treatment conditions (p < .05). PTSD = posttraumatic stress disorder. PE = prolonged exposure; NAL = Naltrexone; PBO = placebo; SC = supportive counseling.
a
The percent mediation did not apply because the sign of the indirect effect and the total effect was opposite in both cases.
*
p < .05.
**
p < .01.
***
p < .001.