Four large Iowa hospital and clinic groups have agreed to be paid for improving Medicare patients' health instead of just expecting more federal money every time they provide another test or procedure. The health systems are creating "accountable care organizations." Medicare officials plan to announce that new contracts have been signed with organizations associated with Genesis Health System, based in the Quad Cities; Iowa Health System, based in Des Moines; Mercy Medical Center in Des Moines; and the University of Iowa Hospitals in Iowa City.