Medicare's new crackdown on readmissions will hit hospitals that treat large numbers of low-income patients especially hard, a Kaiser Health News analysis shows. The KHN analysis separated hospitals into four groups based on an index that the Centers for Medicare & Medicaid Services uses to decide whether a hospital deserves extra payments for treating large numbers of low-income patients. One hundred hospitals in the group with the most poor patients—12 percent—will receive the maximum penalty from CMS: a 1 percent decrease in their reimbursements starting in October. By contrast, only 47 hospitals, or 6 percent, in the group with the fewest poor patients will receive the maximum penalty, the data show.