Methods: In contrast to a systematic review, the intent of a scoping review is to broadly review the literature to examine the extent, range, and nature of research activities and to identify gaps. We systematically searched relevant databases with the guidance of a reference librarian. We comprehensively searched key terms related to I/DD, disability, and Medicaid. These key terms were truncated and broadened to enable comprehensive coverage per guidelines of scoping review methodologies as well as to account for changes in disability diagnosis language. Studies were included in our review if they: (1) included participants with I/DD; (2) focused on Medicaid; (3) quantitatively tested an aspect of Medicaid policy on a given outcome.
Results: We identified 764 unique studies, of which 11 were eligible for inclusion. All eleven studies examined an area of Medicaid policy and its impact on an outcome for those with I/DD. Six of the studies examined the effect of a state policy on outcomes for children, adults, and parents within the state. Five of these studies looked at specific state waiver programs. The remaining five studies used national level data to compare outcomes across states and counties. Most of the studies (n=9) assessed the cost implications of a Medicaid policy change and more than half of the studies looked at the effect of a state waiver or HCBS program. No studies utilized causal modeling.
Conclusions and Implications: Findings of this review suggest that research on the economic and social impact of HCBS waivers is emerging, yet more research is needed to determine causal mechanisms. Key findings of the eleven studies in this review demonstrate that state-level Medicaid programs are improving the lives of those with I/DD and their families. Research that examines the differences between state HCBS waiver programs is now needed to determine which aspects of these programs are working most efficiently and effectively, and for whom.