Study design
We used de-identified public-use data from the 2019 National Survey on Drug Use and Health (NSDUH) for this study. Details of the construction of the samples, survey questions, and survey administration can be found in the Center for Behavioral Health Statistics and Quality [25] and Substance Abuse and Mental Health Services Administration (SAMHSA) [26]. The NSDUH is an annual cross-sectional survey in the U.S that uses a complex, multistage area probability sample of the U.S. civilian, noninstitutionalized population in each of the 50 states and the District of Columbia. This survey assesses substance use and mental health among the population. The data consists of a total of 56,136 individuals aged 12 years and older. We, however, conducted our analysis on adults aged 18 years to 64 years of age, which consists of a total of 38,841 adults with complete data on receiving opioid medication-assisted treatment (MAT) status. Only adults aged 18–64 years were considered in our analysis because individuals aged 12–17 years or 65-plus years had no MAT use prevalence in the dataset.
Measures
Dependent variable
The dependent variable is receiving opioid MAT status, which was self-reported. The participants were asked to indicate whether they had received opioid MAT in the past year (yes/no).
Independent variables
We examined four main independent variables: 1) sexual identity, 2) major depressive episode (MDE) symptoms in the past year, 3) past-year alcohol use dependence, and 4) past-year marijuana use dependence. Sexual identity was measured by asking the participants to self-report their sexual identity using heterosexual, lesbian, gay, or bisexual response options. Our analysis categorized the sexual identity responses as heterosexual, lesbian/gay, or bisexual. Due to the limited sample size within groups, we combined lesbian/gay and bisexual participants into one category in Table 3.
MDE symptom status was determined in the NSDUH based on the Diagnostic and Statistical Manual of Mental Disorders 5th edition (DSM-5) [7, 27]. MDE questions measured if participants had experienced an MDE in the past year (see details in Center for Behavioral Health Statistics and Quality [25]). Based on the self-report on the DSM-5 questions, the participant was classified by the NSDUH as having MDE in the past year if the participant had a lifetime MDE and a time in the past 12 months when the participant felt depressed or lost interest or pleasure in daily activities for two weeks or longer, while also having some of the other symptoms for lifetime MDE. Otherwise, the participant was classified by the NSDUH as not having MDE in the past year if the participant had no lifetime MDE or with lifetime MDE but no period of depression lasting two weeks or longer while having other symptoms for lifetime MDE.
Alcohol use dependence was determined with questions based on DSM-4 criteria [26, 28]. A participant was classified with alcohol use dependence if the participant met three or more of the seven DSM-4 alcohol use dependence criteria. Else, the participant was classified as not having alcohol use dependence. These criteria include if the participant: 1) spent a great deal of time over a month or more getting, using, or getting over the effects of alcohol, 2) used alcohol more often than intended or was unable to keep set limits on alcohol use, 3) needed to use alcohol more than before to get desired effects or noticed that same amount of alcohol use had less effect than before, 4) inability to cut down or stop using alcohol every time tried or wanted to, 5) continued to use alcohol even though it was causing problems with emotions, nerves, mental health, or physical problems, 6) alcohol use reduced or eliminated involvement or participation in important activities, and 7) reported experiencing two or more alcohol withdrawal symptoms at the same time that lasted longer than a day after alcohol use was cut back or stopped.
Marijuana use dependence was assessed based on six DSM-4 marijuana use dependence criteria [26, 28]. A participant was classified with marijuana use dependence if they met three or more of the six criteria. Otherwise, the participant was classified as not having marijuana use dependence. The criteria are: 1) Spent a great deal of time over a month or more getting, using, or getting over the effects of marijuana, 2) Used marijuana more often than intended or was unable to keep set limits on marijuana use, 3) Needed to use marijuana more than before to get desired effects or noticed that same amount of marijuana use had less effect than before, 4) Inability to cut down or stop using marijuana every time tried or wanted to, 5) Continued to use marijuana even though it was causing problems with emotions, nerves, mental health, or physical problems, and 6) Marijuana use reduced or eliminated involvement or participation in important activities.
Covariates
Our analyses adjusted for sociodemographic characteristics based on previous studies [10–13]. These variables include age (18–25, 26–34, 35–49, 50–64), sex (male/female), race/ethnicity (non-Hispanic White, non-Hispanic Black/African American, Hispanic, and Other race [non-Hispanic Native American/Alaskan Native, non-Hispanic Asian American, non-Hispanic Native Hawaiian/Other Pacific Islander, and non-Hispanic more than one race]), level of education completed (Twelfth grade or less, High School diploma/GED, some college credit but no degree, Associate's degree, and college graduate or higher), total family income (<$20,000; $20,000 to $49,999; $50,000–$74,999; and ≥ $75,000), and employment status (employed full time, part-time, unemployed, or other [i.e., students, persons keeping the house or caring for children full time, retired or disabled persons, or other persons not in the labor force]). These variables were analyzed as categorical variables in our study.
Statistical Analyses
The data analysis was performed using STATA/SE, version 16.1 [29]. Descriptive analyses were performed to describe percentages of the participants’ sociodemographic characteristics, MDE symptoms, alcohol use dependence, and marijuana use dependence by the status of receiving opioid MAT (see Table 1). We computed bivariate analyses to assess the association between receiving opioid MAT status and sociodemographic characteristics, sexual identity, MDE symptoms, alcohol use dependence, and marijuana use dependence, respectively, using chi-square tests. Furthermore, we conducted a multivariable logistic regression analysis to examine the association between receiving opioid MAT and sexual identity, MDE symptoms, alcohol use dependence, and marijuana use dependence, adjusting for the sociodemographic variables (see Table 2). We examined the association between receiving opioid MAT and sexual identity, MDE symptoms, alcohol use dependence, and marijuana use dependence, adjusting for the sociodemographic variables, among individuals diagnosed with opioid use disorder (OUD) symptoms using multivariable logistic regression analysis (see Table 3). We reported adjusted odds ratios (AORs) and 95% confidence intervals (95% CIs) and considered statistically significant results at p < 0.05 using the Wald test or Wald Chi-Squared Test.
All the analyses, except the frequencies, were weighted using the NSDUH survey weight to obtain nationally representative estimates. The NSDUH survey weight helps obtain weighting and clustering effects such as the unequal probability of sampling, non-response, and post-stratification adjustments [25]. The NSDUH nesting variables were also used to capture explicit stratification, ascertain clustering with the data, and obtain accurate variance estimates [25]. There were 509 (unweighted = 1.31% and weighted = 1.24%) and 826 (unweighted = 2.13% and weighted = 2.25%) missing observations on MDE and sexual identity, respectively. However, this missingness is insignificant and negligible because it is less than 10% to impact our findings [30, 31]. Multicollinearity among the independent variables was also examined using the variance inflation factor (VIF). No significant multicollinearity was found because the mean VIF value was 1.10 [32].