In their quest to establish value for money, payers in the U.S. are asking drug manufacturers to experiment with new contracting models that tie rebates and discounts to health outcomes instead of drug volumes.

At least seven outcomes-based contracts have been disclosed since 2009. The latest was announced in March, when Merck KGaA's EMD Serono Inc. subsidiary and regional pharmacy benefit manager Prime Therapeutics LLC reached a deal for multiple sclerosis drug Rebif interferon beta-1a.