More than half of Medicaid doctors could not offer appointments to Medicaid enrollees, an investigation by the inspector general of the Department of Health and Human Services released on Tuesday revealed.

Despite states and the federal government spending nearly $460 billion on Medicaid in fiscal year 2013, the program has been plagued with access issues due to the fact that the it pays doctors at a low rate. The IG investigation was conducted in the summer and fall of 2013, before Obamacare added millions of additional beneficiaries to the health insurance program for low-income Americans.