(Bloomberg) -- Novartis AG’s plan to link the payment for a newheart-failure treatment to the medicine’s performance is meetingskepticism from the largest manager of drug insurance benefits inthe U.S.

Novartis said Wednesday that it plansto offer an outcomes- based plan for its newly approved drugEntresto. Insurers would initially pay a lower price, followed byan additional payment if Entresto succeeds in keeping patients outof the hospital and reducing associated costs. The drug could cost as much as$4,500 a year and would be taken daily for a patient’slifetime.

The problem is that performance-linked prices are difficult tomanage because so many things can affect a patient’s outcome, saidSteven Miller, chief medical officer of Express Scripts HoldingCo., which helps companies and insurance plans manage theirprescription benefits.

“If patients on this new drug go out and have a salty pizza andend up in the emergency room, is that the drug’s fault or thepatient’s fault?” Miller said by telephone. “If the patient isn’tadherent with taking the drug, is it the drug’s fault or thepatient’s fault?”

The U.S. lacks infrastructure for data collection on patients,and it’s not clear who would be responsible for tracking theiroutcomes, Miller said.

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“These are the discussions we’re having with Novartis -- howwill we actually do this so it’s not burdensome for patients,payers and the pharma industry?” he said.

Miller remains enthusiastic about Entresto, saying it may be a“game changer for heart failure.” Express Scripts is in pricingconversations with Novartis, he said.

CVS Health Corp. is evaluating several pay-for-performance drugplans, said Christine Cramer, a spokeswoman for the second- biggestpharmacy benefit manager in the U.S.

“Given that each of these plans is unique, we evaluate each onebased on what deal would deliver the most value to our clients andtheir members,” she said.

Novartis is still in pricing talks and can’t discuss detailsyet, said Eric Althoff, a spokesman.

“An outcomes-based approach is still aspirational, but notunrealistic,” he said. “While discussions have been encouraging,we’re in the early stages.”

Drugmakers could help create technology to gather data onoutcomes, Althoff said. The company has acknowledged it may bedifficult to get insurers to agree to its plan.

“We can’t make them do this,” David Epstein, head of thecompany’s pharmaceuticals division, told analysts Wednesday. “Myguess is many won’t even want to bother, but it is part of theoffering.”

--With assistance from Simeon Bennett in Geneva.

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