Change Healthcare has confirmed a February ransomware attack on its systems, which brought widespread disruption to the U.S. healthcare system for weeks and resulted in the theft of medical records affecting a “substantial proportion of people in America.” In a statement Thursday, Change Healthcare said it has begun the process of notifying affected individuals whose information was stolen during the cyberattack. The health tech giant, owned by U.S. insurance conglomerate UnitedHealth Group, pro...