The 2021 edition of the RUPRI Center's annual report on Medicare Advantage (MA) enrollment shows that as of March 2021, 42.8 percent of eligible Medicare beneficiaries were in an MA plan. The proportion of metropolitan enrollment (44.6 percent) is higher than that in nonmetropolitan counties (34.6 percent) but the rate of growth in enrollment has been higher in nonmetropolitan counties every year since 2018.

Nearly half (48.9 percent) of nonmetropolitan MA enrollees are in local Preferred Provider Organization plans which have seen relatively steady growth since at least 2009. Nonmetropolitan enrollment in Health Maintenance Organization (HMO) plans has also seen steady growth during that time with 36.8 percent of enrollees in such a plan in March 2021. Well over half of metropolitan MA enrollment has been in HMO plans over the past 10 years (63.0 percent in 2021). This rate of enrollment has been relatively steady for more than 10 years. Nearly all of this growth has corresponded with declining enrollment in Private Fee-for-Service plans which accounted for 0.2 percent of enrollees overall in March 2021.