People with mental retardation (MR) have experienced increasing levels of participation in community life over the past forty years since the era of de-institutionalization. This freedom has facilitated access to alcohol and other drugs (AOD) and thus the potential for developing AOD disorders. Although limited access to AOD treatment for this population is documented, little empirical research is available. This is the first large-scale study of this population that provides demographic information and examines the AOD treatment process vis-à-vis initiation of treatment and engagement in treatment. AOD treatment initiation and engagement are explored for a nationwide sample of Medicaid beneficiaries with MR and a comparison group without MR.

Using a cross-sectional design, research questions about AOD treatment initation and engagement were examined through the analysis of administrative claims data for Medicaid beneficiaries aged 12-99 with and without MR. Sub-group analyses were also conducted for members of the sample and comparison groups with co-occurring serious and persistent mental illness (SPMI). Demographic, clinical and treatment-related information on people with MR, who are normally excluded from AOD-related studies, is accessible via the use of administrative claims data. The study also draws on a set of AOD treatment performance measures designed for use with administrative claims data. These measures were initially developed by the Washington Circle and then further adapted by the National Committee on Quality Assurance for inclusion in the Health Plan Employer Data Information Set (HEDIS).

Among those with MR and AOD issues (N=9,484), 24.6% initiated treatment and 52.6% engaged in treatment. Among those without MR but with AOD issues (N=915,070), 29.3% initiated treatment and 55.9% engaged in treatment. Among those with MR, AOD issues and a SPMI (N=5,809), 26.4% initiated treatment and 51.3% engaged in treatment. Among those without MR but with both AOD issues and a SPMI (N=292,785), 31.7% initiated treatment and 53.2% engaged in treatment. In both groups, statistically significant differences were found regarding initiation, with those without MR entering treatment at higher rates. Engagement rates were not different at a statistically significant level.

Aiding practitioners and policymakers in the clinical arena of AOD treatment and disability, implications relate to how existing systems provide AOD-related care to people with MR and point to areas in which improvements in access to and quality of AOD treatment are needed. Findings suggest that although people with MR may access AOD treatment at lower rates, possibly a function of access, treatment engagement rates are essentially equal. AOD treatment engagement is predictive of treatment retention, which is also linked to better recovery outcomes; that people with MR who have AOD problems engage at the same rate as the comparison group is encouraging vis-à-vis the potential for positive treatment outcomes, although improvements are needed in access to AOD treatment for this population.