GAO-15-460, Medicaid: A Small Share of Enrollees Consistently Accounted for a Large Share of Expenditures

In this report released in May 2015 the Government Accountability Office (GAO) analyzed data from the Medicaid Statistical Information System (MSIS) obtained from the Centers for Medicare and Medicaid Services (CMS) for fiscal years 2009, 2010, and 2011. The MSIS file contained information on expenditures by service category, payment arrangements, basis for Medicaid eligibility, and demographics for each Medicaid enrollee.

In fiscal years 2009 through 2011, the most expensive 5% of Medicaid-only enrollees accounted for 48% of Medicaid expenditures. Of those in the most-expensive 5% of Medicaid-only enrollees, an average of 51.3% had a mental health . . .