SALEM, Ore. — Oregon health officials are concentrating on coordinating services and preventing hospital stays. New Jersey medical centers are rewarding doctors who can save money without jeopardizing patient care. And Massachusetts is expanding the role of physician assistants and nurse practitioners. As states work on implementing the complex federal health care reforms, some have begun tackling an issue that has vexed employers, individuals and governments at all levels for years — the rapidly rising costs of health care. The success of models that are beginning to emerge across the country ultimately will determine whether President Barack Obama's Affordable Care Act can make good on its name.