Description: Seniors enrolled in Medicare plans that charge higher co-pays for brand name or non-preferred medications fill almost 15 percent fewer prescriptions than their peers who have a flat co-pay for all prescription medications, a new study finds.

The data highlights a tough decision for older Americans: Spend more or skip some of their medicines, including those for chronic diseases such as diabetes and high blood pressure.

"Consumers are sensitive to price. When they have to pay more, they tend to consume less," senior researcher Boyd Gilman said in a prepared statement.

Gilman and colleagues at Cambridge, Mass.-based Mathematica Policy Research Inc, analyzed spending on prescription drugs among almost 353,000 Medicare beneficiaries with employer-sponsored retiree drug coverage.

They compared spending by those in single-tiered plans to those in three-tiered prescription drug plans. Three-tiered plans charged retirees higher co-pays for usi