STASH, Vol. 20(8) – The prevalence of co-occurring substance use disorders among people with opioid use disorder

Comorbid substance use is associated with poor health outcomes for people with opioid use disorder, including consequences such as heightened risk for overdose and mortality. While treatment guidelines recommend screening people with opioid use disorder for comorbid substance use disorders, very few people actually receive such care, which means many experience poor clinical outcomes. This week, STASH reviews a study by Thomas Santo Jr. and colleagues that examined the prevalence of lifetime and current comorbid substance use disorders among people with opioid use disorder.

What was the research question?
What is the prevalence of concurrent substance use disorders among people with opioid use disorder?

What did the researchers do?
The researchers conducted a systematic review and meta-analysis of articles that estimated the prevalence of concurrent substance use disorders among people with opioid use disorder. They searched three scientific databases from 1990 to 2022 for studies that provided this information. First, they conducted a random-effects meta-analysis to estimate lifetime and current (e.g., past-year) prevalence rates across all the studies. Then, they conducted meta-regressions to examine whether there were differences in prevalence rates due to different sample characteristics, such as the type of substances participants used and participants’ geographic location.

What did they find?
The researchers included data from 194 studies and a total of 77,212 participants with opioid use disorder. Of these people, 72% experienced a comorbid non-opioid substance use disorder in their lifetime. Most (59.5%) of the participants were currently experiencing a non-opioid substance use disorder. The most commonly co-occurring substance use disorders among people with opioid use disorder were (1) cocaine use disorder, (2) alcohol use disorder, (3) cannabis use disorder, (4) sedative use disorder, and (5) methamphetamine use disorder (see Figure).

Figure. This figure depicts the prevalence of co-occurring substance use disorders among people with opioid use disorder. Click image to enlarge.

Why do these findings matter?
These findings indicate that the majority of people with opioid use disorder experience another kind of substance use disorder at the same time. As such, the results of the study indicate a significant need to improve treatment services for people with opioid use disorder, particularly by routinely screening for the potential that someone is experiencing multiple substance use disorders simultaneously. Relatedly, the high prevalence of comorbid substance use disorders suggests the need to develop comprehensive interventions that target polysubstance use.

Every study has limitations. What are the limitations in this study?
Most studies that were included in the meta-analysis were from North America, which means that its results cannot be generalized to other places with different patterns of substance use and treatment. Additionally, the researchers collected articles from a thirty-two year time period (1990-2022), but they did not conduct analyses to assess whether the prevalence of comorbid substance use disorders changed over time. Because of this, the results are inconclusive as to whether comorbid substance use was more or less common during different waves of the opioid epidemic. This is important because different waves of the opioid epidemic are characterized by use of different types of opioids (e.g., prescription pills, fentanyl) and occurred at different points in time. With this being the case, it is unclear, based on the results of this study, whether comorbid substance use is more or less prevalent now compared to the beginning of the opioid epidemic. Similarly, it is unclear whether people who use different types of opioids are more or less likely to have comorbid substance use disorders.

For more information:
If you are worried that you or someone you know is experiencing addiction, the SAMHSA National Helpline is a free treatment and information service available 24/7. For more details about addiction, visit our Addiction Resources page.

— Seth McCullock, PhD