(Photo: Michael Nagle/Bloomberg)

Health insurer UnitedHealth closed 2023 with a medical loss ratio of 85% in the fourth quarter, which was its highest ratio since the pandemic began in early 2020. The company's medical costs, its largest expense, jumped to $62.23 billion in the quarter, up from $53.6 billion at the end of 2022.

Medicare Advantage claims were responsible for much of the increased costs. UnitedHealth covers about 7.7 million people with Medicare Advantage plans, and many of them received heart and orthopedic outpatient procedures, UnitedHealth said. Later in the quarter, it also saw an increase in seasonal activity as more seniors sought vaccinations for the respiratory virus RSV, which sometimes led patients to receive additional care. "Seniors did really respond strongly to RSV vaccinations and scheduled physician visits," CFO John Rex said.