Results of Cox PH regression analyses using interpersonal childhood trauma to predict alcohol use initiation are shown in the second and third columns of Table 4. No violations of PH assumptions were observed in either model. In Model 1, interpersonal childhood trauma was associated with elevated likelihood (hazard ratio (HR)=1.70, 95% confidence intervals (CI):1.44–2.01) and Black race with lower likelihood (HR=0.58, CI:0.51–0.66) of initiating alcohol use. There was no evidence for an interaction between race and childhood trauma. The addition of SES indicators and neighborhood factors in Model 2 resulted in a significant reduction in hazard ratios (i.e., point estimates were outside the bounds for the CIs in Model 1) for both childhood trauma (HR=1.36, CI:1.05–1.76) and race (HR=0.67, CI:0.55–0.81). Null effects for receipt of public assistance, primary caregiver education level <12 years, and neighborhood factors were observed. Both a main effect (HR=1.27, CI:1.01–1.60) and an interaction with race were observed for single–paren-household status (HR=0.73, CI:0.54–0.99) (see Supplemental Figure 1), indicating that living in a single-parent household is associated with elevated likelihood of initiating alcohol use exclusively in White girls.
