Statistical Analysis
Three offspring groups were identified based on the number of biological parents with AUD: non-AUD parents, 1 AUD parent, and 2 AUD parents. The 3 groups were compared for sociodemographic characteristics using χ2 analysis for categorical variables. The prevalence rates of lifetime AUD in the 3 offspring groups were calculated using cross-tabulations.
We conducted logistic regression and tetrachoric correlations to evaluate the effect of the number of AUD parents on lifetime AUD in offspring (main outcome variable). First, unadjusted ORs and 95% CIs were calculated. Second, the 5 sociodemographic variables found to be statistically significant on the initial χ2 analyses (gender, age, race, education, and personal income) were entered into the logistic regression analysis to estimate adjusted odds ratios (AORs) and 95% CIs.
For subgroup analysis stratified by gender, we first split the sample by gender and repeated logistic regression to examine the effect of the number of AUD parents on offspring with lifetime AUD in the 3 offspring groups. Male and female offspring were compared with same gender offspring in the 3 groups. Second, without splitting the sample by gender, we calculated interaction effects between gender and number of AUD parents in logistic regression models to examine if the gender variable modified the effect of the number of AUD parents on AUD in offspring. Statistical analyses were performed with IBM SPSS Statistics, version 19 (IBM SPSS; Armonk, New York).