An Issue Brief from the Commonwealth Fund examines coverage trends for Medicare beneficiaries between 2010 and 2016, looking at rates of coverage under employer-sponsored insurance, Medigap supplemental plans, and private Medicare Advantage plans. The proportion of beneficiaries with supplemental employer coverage dropped between 2010 and 2016, particularly for those with low or middle incomes.
The Issue Brief can be obtained at https://www.commonwealthfund.org/sites/default/files/2019-07/Davis_erosion_ESI_Medicare_financial_burden_ib.pdf.