2.1 Protocol
The current study is a secondary analysis of data from a project studying the transdiagnostic risk and maintenance factors of PTSD and hazardous alcohol use among people with probable PTSD and AUD. The participants for this project consist of a nationally representative sample of adults recruited through Qualtrics Panels, an online data collection platform. Participants first completed eligibility screening questionnaires and then provided voluntary informed consent to participate in the study. Eligibility criteria for the study were as follows: being between the ages of 18 and 65, having access to a computer or mobile device, endorsing symptoms consistent with probable PTSD based on a score of 3 or above on the Primary Care PTSD Screen (PC-PTSD; 22), and having probable AUD based a score of at least 3 for females or 4 for males on the three-item Alcohol Use Disorders Identification Test (AUDIT-C; 23). The exclusion criteria for the study were inability to provide voluntary informed consent, inability to complete online surveys, and lack of English proficiency. Participants were compensated for completing the baseline assessment through cash-based incentives, reward miles, or reward points. This study was approved by the University of Houston Institutional Review Board.
2.2 Participants
Participants included 565 who screened positive for probable PTSD and AUD. The biological sex composition was 52.2% female. The racial and ethnic composition was 68.8% Non-Hispanic White, 15.2% Black or African American, 8.8% Hispanic White, 3.0% Asian, 1.4% Native American/Alaskan Native, 0.5% Native Hawaiian or Pacific Islander, and 2.1% Other. The mean age of the sample was 39.2 years (SD = 10.9).
2.3 Measures
2.3.1 Demographics were measured using a self-report questionnaire that included age, biological sex, gender identity, ethnicity, race, education, occupation, living situation, and income.
2.3.2 The All Aspects of Health Literacy Scale (AAHLS; 24) is a 14-item, self-report questionnaire used to assess health literacy. In the current study, the FHL subscale score was used, which is derived by calculating the mean of the three health literacy items of the subscale. Cronbach’s α for this subscale, using items 1 and 3 in accordance with Chin & McCarthy (24), was .803.
2.3.3 The Alcohol Use Disorders Identification Test (AUDIT; 25) is a 10-item self-report questionnaire used to assess alcohol consumption, drinking behaviors, alcohol-related problems, hazardous alcohol use, and harmful alcohol use. In the current study, the AUDIT total score was employed to assess hazardous alcohol use. This scale demonstrated good internal consistency (Cronbach α = .894).
2.3.4 The PTSD Checklist for DSM-5 (PCL-5; 26) is a 20-item self-report questionnaire used to assess past month PTSD symptom severity. Participants identified their worst traumatic event using the Life Events Checklist for DSM-5 (LEC-5; 27) and indicated their level of distress for that event for each symptom using a 5-point Likert-type scale ranging from 0 (not at all) to 4 (extremely). The items were summed to create a total score. This item demonstrated excellent internal consistency (Cronbach α = .964).
2.4 Data Analytic Plan
First, predictor variables of interest (PCL and FHL) were mean centered. Second, correlation coefficients were calculated to examine the associations between the study variables. Third, linear regressions were conducted regressing AUDIT total score onto PCL total symptoms and FHL total score. Finally, the interaction term between FHL and the PCL was added in the third step of the regression models. Age, biological sex, and race were included as covariates in the models. Participants who had missing data on variables of interest were excluded from the analyses.