The most expensive 5% of enrollees accounted for almost half of annual Medicaid expenditures for Medicaid-only enrollees in fiscal years 2009 through 2011, according to a report released Friday by the Government Accountability Office. Although fewer than 10% of Medicaid-only enrollees, disabled enrollees represented about 64% of this high-expenditure group, ranging from 39% in Connecticut to 95% in Tennessee. Conversely, children represented about half of Medicaid-only enrollees but only 16% of this high-expense group. Looking at certain chronic conditions or services, the study found 53% of high-expenditure Medicaid-only enrollees had mental health conditions, 20% substance abuse, 19% diabetes and 14% asthma. The report was requested by leaders of the Senate Finance Committee.