CHICAGO--(BUSINESS WIRE)--Fitch Ratings has affirmed the 'AA+' rating on approximately $4.1 billion of Senior Credit Group Bonds issued on behalf of Ascension Health Alliance (Ascension) through various conduit issuing authorities and approximately $425 million of Ascension taxable bonds. Additionally, Fitch Ratings has upgraded the rating on approximately $489 million of Ascension Subordinate Credit Group bonds to 'AA+' from 'AA'. The upgrade of the subordinated bonds reflects Ascension's stro