Medicare pays for the bulk of the medical care for Americans over 65, but a lot of their income is still eaten up by medical expenses. The list of expenses is long. The lion’s share goes toward various insurance premiums – for Medicare Part B coverage, Part D prescription drug coverage, and supplemental insurance, whether Medigap, a Medicare Advantage plan, or employer health insurance for retirees. The remaining costs, for copayments and deductibles, are also significant. These out-of-pocket costs, when added together, averaged about $4,300 annually per person, finds a new study by researchers Melissa McInerney, Matthew Rutledge, and Sara Ellen King of the Center for Retirement Research. Out-of-pocket costs consume a third of the amount that retirees receive from Socia…