Medicaid OUD Treatment Continuity Study

The study was approved by the Brandeis University institutional review board and was deemed exempt for the need for informed consent by the Washington State Department of Social and Health Services institutional review board because the data were deidentified, in accordance with 45 CFR §46. The report follows the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guideline for case-control studies. We examined Medicaid outpatient, inpatient, residential, and pharmacy claims from Washington State for 2016 to 2019. Using a clinically driven approach, we captured people who may not have been administratively deemed to have a disability for access to income supports and Medicaid, but who had reached a clinical threshold for diagnosis. Washington is a Medicaid expansion state, with a full continuum of SUD care, including all types of MOUD. For each year, we included adults aged 18 to 64 years with an OUD diagnosis who were continuously eligible for full Medicaid benefits for 12 months, to observe full service use. We defined OUD as at least 1 claim for outpatient, inpatient, or residential services with an OUD diagnosis code in a calendar year (eTable 1 in Supplement 1). We excluded 2587 people eligible for both Medicare and Medicaid because Medicare services were unobservable, 1132 people with a benzodiazepine prescription during the same year because concurrent MOUD is associated with increased risk of adverse effects,^{23 (link)} and 132 people because prescription days supply was missing (eFigure in Supplement 1). Analyses of MOUD treatment continuity required continuous 6 months of data following the first evidence of MOUD, requiring a look back for claims occurring in the first week of the year to see whether they were the end of an earlier episode.