Medical costs for enrollees in the health-care law’s high-risk insurance pools are expected to more than double initial predictions, the Obama administration said Thursday in a report on the new program.

The health-care law set aside $5 billion for a Pre-Existing Condition Insurance Plan, meant to provide health insurance to those who had been declined coverage by private carriers. Since its launch last summer, nearly 50,000 Americans have enrolled in the program.

The PCIP program will phase out in 2014, when insurers will be required to accept all applicants regardless of their health-care status.

Those who have enrolled in the program are projected to have significantly higher medical costs than the government initially expected. Each participant is expected to average $28,994 in medical costs in 2012, according to the report, more than double what government-contracted actuaries predicted in November 2010. Then, the analysts expected that the program would cost $13,026 per enrollee.