However, this recent 9/29/2011 New York Times article suggests otherwise, "Why Doctors Order So Many Tests".
Of course, some of this is driven by defensive medicine (i.e., to avoid malpractice lawsuits) or by heightened patient expectations that the doctor "do something". But the article also notes this "unintended consequence":
Most notably, more than half the doctors believed that the current quality measures and clinical guidelines endorsed by health care experts and insurers as a way to rein in excesses were in fact having the opposite effect. The guidelines might, for example, require that patients with high blood pressure and diabetes have a specific blood test every three months and take high blood pressure medications as soon as their blood pressure exceeds 140. Because insurers are increasingly linking payment to these guidelines, physicians must strictly follow the quality measures to be paid, regardless of the patient's specific situation. Ironically, most of these quality measures are based on, well, more testing and treatments...Another interesting point is that these extra tests are not typically driven by physician greed (i.e., to generate extra revenue by ordering tests where they have a financial incentive).
"Many doctors feel like they are on a treadmill and are running scared because of malpractice and having to check off all the checkboxes of quality measures," Dr. Chou said. "They feel like they are in an oppressive situation that they can’t do anything about."
It should be no surprise that costs rise the more that government handcuffs physicians and attempts to override their independent judgement with one-size-fits-all "practice guidelines". These practice mandates remove that physicians mind from the equation. Rigid bureaucratic thinking does not lead to innovation and savings in business. There's no reason to think that it will lead to innovation and savings in health care, either.
(Read the full text of "Why Doctors Order So Many Tests".)