Mental Health and Substance Use Disorder Comorbidities Among Medicaid Beneficiaries: Associations with Opioid Use Disorder and Prescription Opioid Misuse

Background and Purpose: Medicaid insures about one-fourth of the US population and disproportionately insures about 38% of non-elderly adults with opioid use disorder (OUD). Owing to Medicaid’s prominent role in insuring persons with an OUD and that Medicaid coverage includes pharmaceutical benefits, there has been considerable interest in studying potential prescription opioid misuse among Medicaid beneficiaries and identifying subpopulations at higher risk for misuse and possible progression to an OUD, including those with co-occurring substance use (SUD) or mental health disorders (MHD). In this study, we examined patterns of co-occurring SUDs and MHDs among Medicaid beneficiaries with varying levels of opioid use and misuse to determine medical complexity and to consider the possible implications for improving medication-assisted treatment (MAT) outcomes.

Methods: We analyzed 2018 Illinois Medicaid claims data for 1,102,479 adult beneficiaries 18 to 64 years old. Using algorithms based on previous studies, we determined the presence or absence of 9 SUDS (including OUD) as well as 9 MHDs and likely prescription opioid misuse. We then subdivided the beneficiary sample into 5 groups: those who were prescribed opioids and evidenced either no, possible, or probable misuse; those evidencing an OUD; and those evidencing no opioid use or misuse. Multinomial logistic regressions were used to compare the five subgroups on the relative risks for co-occurring SUDS/MHDs.

Results: Persons with no opioid use/misuse were at the lowest relative risk for co-occurring SUDs and MHDs, with a slight increase in risk for beneficiaries with possible prescription opioid misuse. Conversely, beneficiaries with an OUD were at highest relative risk for most co-occurring SUDs, but especially for sedative use disorder (rrr=63.5, 95% CI=[56.59, 71.23]), cocaine use disorder (rrr=32.4, 95% CI=[30.81, 34.15]), and other stimulants (rrr=16.7, 95% CI=[15.25, 18.19]). Whereas beneficiaries with an OUD were also at high relative risk for multiple co-occurring MHDs, those with probable prescription opioid misuse had comparable or higher relative risks for the following MHDs: anxiety disorder (rrr=8.6, 95% CI = [8.08, 9.21]), PTSD (rrr=8.1, [95% CI = 7.2,9.1]), and ADHD (rrr=7.9, 95% CI = [6.57, 9.22]).

Conclusions and Implications: Co-occurring MHDs among persons misusing prescription opioids could be important risk factors for opioid prescription misuse and progression to developing an OUD. On the other hand, polypharmacy and co-occurring SUDs appear to be highly associated with but not causally related to having an OUD and could develop synchronously with increased opioid use over time. Additionally, the medical complexity of persons with an OUD and those misusing prescription opioids are likely significant barriers to recent attempts to expand buprenorphine provision as medication-assisted treatment (MAT) for Medicaid beneficiaries. We found that a person insured through Medicaid seeking MAT for their OUD is highly likely to present with multiple co-occurring SUDs and MHDs, which would require case management, multiple treatment referrals, and coordinated community-based behavioral health care interventions in addition to the provision of medication. In this context, social workers could provide these much-needed adjunct but critical services for beneficiaries receiving MAT, thereby potentially improving treatment retention rates and outcomes.