Table 3.
Negative binomial regression models depicting the joint effect of perceived stress and TNFm on cigarette consumption at age 20 (N = 382).
| Cigarette consumption (age 20) |
||||
|---|---|---|---|---|
| Model 1 |
Model 2 |
|||
| b | IRR | b | IRR | |
| Perceived stress (age 19) | .387** (.137) |
1.473 | .369** (.137) |
1.447 |
| TNFm | −.331 (.221) |
.718 | ||
| Perceived stress (age 19) × TNFm |
−.214* (.103) |
.807 | ||
| Supportive parenting (ages 11-13) | −.076 (.113) |
.926 | −.087 (.109) |
.917 |
| Sex (1= males) | 1.928** (.258) |
6.877 | 1.925** (.255) |
6.854 |
| SES-risk (ages 11-13) | .193 (.129) |
1.213 | .180 (.118) |
1.197 |
| Cigarette consumption (ages 11-14) | .141 (.175) |
1.152 | .157 (.190) |
1.171 |
| Factor 1 cell-type | .173 (.111) |
1.189 | .393* (.167) |
1.481 |
| Factor 2 cell-type | −.078 (.110) |
.925 | .131 (.164) |
1.140 |
| Factor 3 cell-type | .089 (.093) |
1.093 | .029 (.093) |
1.030 |
| Factor 4 cell-type | .061 (.097) |
1.063 | .020 (.107) |
1.021 |
| Log of CRP | .192† (.106) |
1.211 | .168 (.107) |
1.182 |
| Constant | −2.006** (.227) |
−2.049** (.222) |
||
| −2LL | 614.638 | 609.992 | ||
| ∆ Chi-square (df = 1) | 4.646* | |||
Notes: Unstandardized (b) shown with robust standard errors in parentheses; IRR = incident rate ratio; supportive parenting (ages 11-13), SES-risk (ages 11-13), cigarette consumption (ages 11-14), factors cell-type, and CRP are standardized by z-transformation (mean = 0 and SD = 1).Using KHB methods (Breen, Karlson, & Holm, 2013), the test of the indirect effect of supportive parenting (ages 11-13) on cigarette consumption (age 20) through perceived stress (age 19) is significant [indirect effect = −.071, 95%(−.132, −.010)].
†
p ≤ .10,
*
p ≤ .05,
**
p ≤ .01 (two-tailed tests).