Mayo Clinic is no longer accepting some Medicare and Medicaid patients, raising new questions about whether it is too selective to serve as a model for healthcare reform. Mayo officials said that the move was a business decision that had grown out of longstanding concerns about what it sees as underpayment by Medicare and Medicaid. The White House has repeatedly held up for praise Mayo and other medical centers that perform well in Dartmouth College rankings showing wide disparities in how much hospitals spend on Medicare patients, the Washington Post reports.