One of the central features of a value-based healthcare insurance system is a financial “stick.” If patients insist on medical procedures that science shows to be ineffective or unnecessary, they’ll have to pay for all or most of the cost.

The article in Reuters Health presents the case of Tanner Martin as an example. When the 17 year old developed excruciating back pain last year, he was sure he needed an X-ray to find out what was wrong. So was his mother, who worried that the pain might indicate a serious injury that could cause permanent disability. In Tanner’s case, when he and his mother went to the San Luis Valley Regional Medical Center in Alamosa, Colorado, they were invited to watch a short video first. The best approach to back pain like Tanner’s, it explained, is stretching, strength-building and physical therapy; X-rays and MRIs, according to rigorous studies, are unlikely to make a difference. If they insisted on the X-ray, they would have to pay $300 on top of the basic cost. They passed on the imaging, knowing they could change their minds if Tanner’s condition worsened. After three weeks of therapy, his back was as good as new.

The additional cost when patients choose procedures that research shows are unlikely to help their condition is a key element of San Luis Valley’s two-year experiment in value-based insurance, the premise of which is that a mix of financial carrots and sticks can steer patients toward medical services that will help them and away from ineffective or unnecessary ones. Starting in 2014, Engaged Public, the Denver research and consulting firm that designed the study, will scrutinize the two years of data to see what effects the novel plan had on healthcare costs and outcomes.

Healthcare policy wonks have been studying value-based insurance for a decade. For some consumer groups, the concept raises concerns over whether it will deter people from treatment when certain procedures are needed. But the idea has gained momentum since the passage of President Barack Obama’s healthcare reform law, which includes provisions to control healthcare spending that now tops $2.7 trillion a year in the United States. About one-third of that is attributed to wasteful or ineffective care. Among the provisions is one that allows state Medicaid programs to adopt value-based designs, as two, in Michigan and South Carolina, have. At least one private insurance plan sold in an “Obamacare” marketplace has done so as well. In addition, Obama’s Affordable Care Act encourages doctors and hospitals to form Accountable Care Organizations (ACOs), which are paid more under the Medicare program for older Americans if they control costs while also providing quality care. Some 4 million Medicare enrollees are now in one of the nation’s nearly 500 ACOs, and private insurance plans are adopting them as well. Medicare now penalizes hospitals if a patient is re-admitted for the same condition within 30 days.

Advocates of value-based insurance say that while focusing on the “supply side” – hospitals and doctors – is a good start, healthcare spending reforms must also involve the “demand” side: patients. For one thing, they say, patients who know they’re on the hook for care that won’t benefit them are less likely to badger their providers. “If someone goes to the doctor and really wants antibiotics for a cold or an MRI for back pain, it can take more time to talk him out of it than to order it,” said Dr. David Downs, medical director of Engaged Public.

The success of value-based insurance’s disincentives is far from assured and has some worried over the extent to which procedures would be considered off-limits. “We have reservations about financial obstacles that might keep patients from getting care they need,” said Joyce Dubow, senior healthcare reform director at AARP, the research and lobbying group formerly known as the American Association of Retired Persons. AARP is a partner in Choosing Wisely, a program in which medical specialty groups identify procedures – more than 200 so far – that do not benefit patients, according to rigorous scientific evidence. The list is a benchmark for discouraged procedures in value-based insurance plans.

The very idea that some diagnostic tests and treatments might not help patients comes as a shock to many Americans. The Choosing Wisely message is difficult to convey to the many patients who “think that when it comes to medical care newer is better and more is better,” said Dr. Yul Ejnes of Brown University’s Alpert Medical School. “So when patients have more skin in the game (in terms of cost), they’re more likely to ask, do I really need this?”