Genesis Health System announced Tuesday that it has signed a contract with Wellmark Blue Cross Blue Shield to set up an accountable-care organization. Wellmark announced in April that it had signed similar contracts with Iowa Health System and Mercy Medical Center-Des Moines. The idea is gaining steam nationally, largely because of incentives from the federal health reform law. University Hospitals in Iowa City and Mercy Medical Center-Cedar Rapids, which are working together to form such an organization, signed on with Medicare. A Genesis spokesman said his system hopes to sign a similar contract with Medicare in the next few weeks.