Too young to qualify for Medicare and rarely covered by employers, healthy early retirees can face healthcare premiums that are triple or more what they paid while working. Others, who suffer from middle-age ailments like arthritis or back pain, wind up paying far more, if they aren't simply rejected. Researchers at the Commonwealth Fund found that in 2007 about 35% of people between the ages of 50 and 64 were uninsured or underinsured, up from 26% five years ago.