The average prices of drugs that elderly Americans use most often rose more than twice as fast as general inflation last year, according to survey results released Tuesday. It’s the third straight year those prices have risen so dramatically, said officials from AARP, which conducted the study.

The increase in average price for 195 brand name drugs commonly used by the elderly was 6.6%, or more than double the 3.1% rise in general inflation (as measured by the Consumer Price Index). By comparison, the average price of generic drugs rose less than 1%, also keeping with a recent trend, according to AARP.

The findings show there’s more pressure ahead for the Medicare program, which will start paying for a new prescription drug benefit in January, said Stephen Schondelmeyer, the University of Minnesota drug-price expert who analyzed the study findings.

A spokesman for pharmaceutical manufacturers disputed the findings, saying they did not take common discounts into effect nor reflect true prices seniors pay. A spokeswoman for a major pharmaceutical managed care company, however, said the 6.6% figure was “generally” what her company was experiencing. The study examined buying by the general public and did not take into account buying processes that most nursing homes use.