The Chicago-based Mercy Health System has become part of Trinity Health, the Novi-based Catholic healthcare system said Monday. The affiliation with Trinity Health, finalized Sunday, will help Mercy Hospital in Chicago survive, the two nonprofit groups said in a statement. Trinity Health, which operates 49 hospital and more than 430 outpatient facilities, has shared some services with Mercy Health since 2009. In November, the two health systems agreed to work more closely together to cut costs and improve service at Mercy Hospital, receiving the necessary regulatory and board approvals.