Trends in and correlates of tranquilizer misuse among adults who misuse opioids in the United States, 2002-2014

Purpose: Almost a third of opioid overdose deaths also involve benzodiazepines, but few representative studies have examined misuse of benzodiazepines and other tranquilizers by adults who misuse opioids. This study estimated the prevalence and frequency of tranquilizer misuse among adults who misuse opioids and examined characteristics associated with tranquilizer misuse. Methods: A sample of adults who misused opioids in the past year (n = 36,043) were identified in the National Surveys on Drug Use and Health 2002-2014. Tranquilizer misuse prevalence was estimated for each year from 2002 to 2014. Data were then pooled for all years. Multiple logistic and Poisson regression was used to identify characteristics independently associated with the prevalence and frequency tranquilizer misuse respectively. Results: Twenty-eight percent of adults who misused illicit opioids in the past year also reported tranquilizer misuse. This prevalence did not change notably over the 13-year period examined. Among those who misused opioids, meeting criteria for opioid abuse or dependence was associated with a 134% increase in the odds of misusing tranquilizers during the same year. Other characteristics associated with increased odds of tranquilizer misuse included being aged 18-25 years, non-Hispanic white, uninsured, unemployed, and having used heroin. Conclusions: Tranquilizer misuse is common among adults who misuse opioids and has not changed substantially over the past decade. Meeting criteria for abuse or dependence of opioids is associated with more than double the odds of tranquilizer misuse among adults who misuse opioids.