NY -- Standard&Poor's CreditWire 1/29/98 -- Standard&Poor's today affirmed its single-'A'-plus counterparty credit rating of United HealthCare Corp. (UHC), and revised its outlook to stable from positive. The rating on Minnetonka, Minn.-based UHC are supported by the company's leading position in the U.S. managed care industry and its solid consolidated financial profile. The outlook change reflects UHC's substantial growth rate achieved over the past few years, and Standard&Poor's view of current and prospective operating company capital needs to support its existing operations and future growth prospects and its recent share repurchase initiatives. Major ratings factors: -- Excellent Business Review. UHC is one of the nation's largest managed care organizations providing health care services and