If you watch an episode of House or Grey’s Anatomy, you might think that the best doctors break rules, disregard guidelines and flout convention... all to make sure their patients get better. They’re cowboys, but they get results.

In reality, doctors who go outside the clinical guidelines rarely actually save lives. But they frequently drive up healthcare costs.

That's the finding of a new study, co-authored by Ariel Stern, David Cutler, Jonathan Skinner, and David Wennberg, which found that clinically-unsupported treatments account for “35 percent of end-of-life spending, and 12 percent of U.S. health care spending.”

And ‘cowboy doctors,’ aren’t pushing the frontiers of medicine. According to Ariel Stern, “what we’re not talking about are these cases where the doctor can go above and beyond and do something that may help the patient, even though it will require a lot of effort and cost. We’re truly talking about a set of interventions for which there’s no clinical evidence that they would be beneficial for the patients that we’re looking at.”

What type of doctor ignores clinical guidelines? Well, Stern says that they display a “strong sense of individualism,” they tend to be male (giving more credence to the nickname cowboy), and they tend to be clustered in places like “Miami, Ft. Lauderdale, and Chicago.” Unsurprisingly, areas with a large number of doctors have much higher healthcare costs, on average.

So, how can these cowboys be roped in? Stern advocates policy changes that encourage physicians to practice according to clinical, evidence-based guidelines, but she’s quick to admit that there’s no “magic bullet” yet.

Still, there's hope. Physicians who move to regions where doctors practice differently tend to start practicing like the physicians they’re close to. High-end medicine meets peer pressure, it might be just what cowboy doctors need.