Retention among Medicaid beneficiaries in opioid treatment programs in California

Continuing medications for opioid use disorders (MOUD) for an extended period is important to achieve good outcomes, but many patients do not remain in treatment for even six months. The goal of this study was to develop and describe case-mix adjusted retention rates among California Opioid Treatment Programs (OTP).

We developed measures of 30-, 90-, and 180-day retention using data from the California Outcomes Management System for Medicaid beneficiaries admitted as an outpatient to an OTP between July 1, 2021 and June 30, 2022. We applied case-mix adjustment to the measures to ascertain whether differences in patient characteristics drive differences in OTP-level retention rates and assessed the proportion of total variance in retention rates attributable to differences between OTPs. Finally, we identified statistically underperforming and overperforming OTPs relative to expected retention based on case-mix and described the potential impact of improvement among underperforming OTPs on overall retention rates.

The average case-mix adjusted OTP-level retention rate (N = 131 OTPs) at 30 days was 76 % (range: 45 %-99 %), at 90 days was 54 % (range: 32 %-91 %), and at 180 days was 40 % (range: 8 %-85 %); only 18 % of OTPs retained at least half of their patients for at least 180 days. The distribution of case-mix adjusted and unadjusted measures was similar, indicating that variation in retention rates was explained by factors other than patient demographic and clinical baseline characteristics. Measures were shown to reliably indicate differences between OTPs across all retention periods, with between-OTP variance accounting for no less than 87 % of total variance in the median OTP. We showed that increasing retention among statistically underperforming OTPs to levels expected given their case-mix would result in an additional 4 %, 5 %, and 7 % of patients retained for 30, 90, and 180 days, respectively.

There is considerable room for improvement in retention. The wide range of retention rates at the OTP level after case-mix adjustment suggests that such improvements are attainable. Efforts should be made to support dissemination of successful strategies to improve retention among OTPs. Policymakers should explore opportunities to facilitate improvement, such as enacting quality reporting programs for OTPs.