NEW YORK (Reuters) - A recently adopted tactic by U.S. health plans to limit the financial assistance drugmakers provide directly to consumers for prescription medicines is taking a toll on drug prices, according to a new analysis released on Tuesday.

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Real U.S. drug prices, including discounts and rebates, fell 5.6 percent in the first quarter of this year, compared to a 1.7 percent drop in the same period a year ago, according to Sector & Sovereign research analyst Richard Evans.

He attributed most of the decline to ‘copay accumulator’ programs introduced by pharmacy benefits managers, who manage prescription drug benefits and negotiate on behalf of insurers and other payers.

If drugmakers cannot find a way to circumvent these programs by next year, Evans said, those declines could double or triple.

As the cost of medications reaches new heights in the United States, drugmakers have increasingly offered so-called ‘copay assistance’ cards, similar to a debit card, that consumers can use at the pharmacy counter to reduce their out-of-pocket costs.

But pharmacy benefits managers such as Express Scripts Holding Co and CVS Health say these payments insulate consumers from the real costs of their drugs and can push them toward more expensive medications when a cheaper option is available.

“Copay card programs can lead to increased healthcare costs in the system by encouraging the use of higher cost, often branded drugs,” CVS said in a statement.

Beginning in January, Express and other pharmacy benefits managers introduced a new ‘copay accumulator’ approach, refusing to allow copay assistance payments to contribute toward a patient’s deductible before insurance kicks in. Evans said that around 17 percent of health plans with 5,000 or more employees are currently using a copay accumulator.

That has forced drugmakers to either keep paying out-of-pocket costs for a consumer, or risk them ditching a medicine because they can no longer pay for it.

“It’s a constant cat and mouse game,” said Express Scripts Chief Medical Officer Steve Miller. “Pharma companies want anything they can get out there that allows them to raise the price of the drug ... Our job is to protect the integrity of the plan.”

But Miller disputed the idea that copay accumulator programs were central to net U.S. drug price declines, saying the entry of competing medications was helping payers such as insurers negotiate better deals.

The companies most vulnerable to the change include makers of costly specialty medications for HIV, rheumatoid arthritis and multiple sclerosis. They include Gilead Sciences Inc, Biogen Inc, Eli Lilly & Co and AbbVie Inc, Evans said.

AbbVie Chief Executive Richard Gonzalez acknowledged that the programs were hurting revenue in April during a conference call to discuss company earnings, but said it was not material to the bottom line. About 4 percent of patients using AbbVie’s blockbuster arthritis treatment Humira were covered by health plans using copay accumulators, he said.

Biogen CEO Michel Vounatsos said in April that the programs had “absolutely no impact” on the company’s sales in the first quarter.

Bernstein analyst Ronny Gal said in April that some companies, including AbbVie and Amgen Inc, have started giving patients prepaid debit cards that cannot be tracked by pharmacy benefits managers, hoping to sidestep the programs.

AbbVie, Biogen and Amgen declined comment on the analyst report released on Tuesday. Representatives for Gilead and Lilly could not be immediately reached.