Characteristics and health care events of patients admitted to treatment for both heroin and methamphetamine compared to patients admitted for heroin only

Introduction: Co-occurring heroin and methamphetamine use is a growing public health problem. This study assessed the characteristics of Medicaid patients admitted to substance use disorder (SUD) treatment programs for heroin and methamphetamine use compared with patients admitted for heroin only. Methods: The study identified patients who entered treatment for heroin and methamphetamine and those admitted for heroin only between 2014 and 2017 from the Oregon Treatment Episode Data Set linked with Medicaid enrollment, and medical and pharmacy claims. We used a cross-sectional design to compare demographics, type of treatment, and substance use characteristics between the two groups. We used logistic regression models to assess differences in the odds of opioid-related and all-cause adverse events. Results: Among the 3802 study sample, 2004 (53%) were admitted for both heroin and methamphetamine use. The heroin and methamphetamine group were more likely to be younger, female, White or American Indian/Alaska Native; and had more comorbidities than patients admitted for heroin only. Patients admitted for heroin and methamphetamine treatment were less likely to receive any medication for opioid use disorder (MOUD) (56% vs 75%, p < 0.001) and received fewer days of MOUD treatment (mean 188 vs. 265 days, p < 0.001) compared to the heroin only group. The heroin and methamphetamine group were more likely to receive buprenorphine (28.1% vs 24.2%) and less likely to receive methadone (39.9% vs 62.5%). The heroin and methamphetamine group began use at a younger age, used and injected more frequently than those admitted for heroin only. Patients treated for heroin and methamphetamine had 17% lower odds of OUD-related adverse events (aOR 0.83; 95% CI 0.70–0.99) and 52% higher odds of all-cause adverse events (aOR 1.52; 95% CI 1.14–2.03) relative to the heroin only group. Conclusion: Patients admitted for both heroin and methamphetamine reported greater addiction severity (more frequent use, earlier onset of use, and injection use), yet less commonly received MOUD compared to those who were admitted for heroin only. These findings indicate substantial missed opportunities for MOUD treatment even among people who successfully engage with the SUD treatment system.