Soaring medical expenditures in the United States are one of the most urgent problems of the American healthcare system and the American economy. Although innumerable commentators have made proposals for reducing expenditures and improving the quality of healthcare, very few have suggested tackling one of the sources of mounting costs: profligate doctors.

Doctors have a common tendency to obtain multiple imaging studies of the same organ when one would suffice, to obtain blood tests of hospitalized patients far more often than necessary, to overuse antibiotics and screening tests or to provide many unnecessary CT scans and back surgeries. The great majority of medical expenditures are under the control of physicians; no one forces doctors to order or do anything.

It doesn’t have to be this way, though. Doctors used to be trained to avoid unnecessary and costly tests. When the residency system was introduced at the Johns Hopkins Hospital in 1889, the faculty emphasized that the goal of residency training was to produce doctors who had razor-sharp problem-solving skills. Virtually every instructor taught that the essence of good problem-solving was to approach a patient’s problem as directly as possible, using the fewest possible tests and procedures, and thereby producing the least disturbance, discomfort and upset. The guideline for performing a test was whether the results would influence the management of the patient, not the mere fact that the test was available.

Surgeons, meanwhile, were not just expected to know how to operate but also on whom, when and when not to operate, thereby saving many patients from unnecessary surgery.

The implications of so-called problem-solving medicine for the health of the nation were profound. Such a practice style provided high quality care with less unnecessary treatment and fewer avoidable side-effects and complications. It was also highly cost-effective, because it consumed fewer resources and cost less money. Problem-solving physicians and surgeons thus served the larger good, for they were acted as effective stewards for the nation’s resources.

What changed all this is was the growing ability and willingness of Americans to pay for medical care. After World War II, more and more expensive technologies were developed, and third-party payers stood willing to cover the costs. Accordingly, residency training and medical practice were conducted in an environment of financial abundance where resources seemed limitless and cost restraint, unnecessary. As a result, faculty members typically encouraged residents to practice extravagantly, obtaining many tests, X-rays and procedures even if they were not needed for the patient at hand.

The result of this approach was a major and unnecessary elevation of the costs of care – both at the teaching hospitals in which residents trained, and subsequently in practice as doctors followed patterns they had learned in training. Decade by decade, as the availability and costs of medical technologies inexorably grew, the economic consequences of such an indiscriminate practice style also grew, as did a concomitant deviation of physicians’ gaze from the bedside to the laboratory.

Today, we operate in a $3tn health economy consuming more than 18% of the GDP in the US. Many experts have documented that doctors provide a significant excess of care, and greater than 30% of all healthcare expenditures are thought to be unnecessary. Of course, many factors, such as “defensive” medicine (ordering unnecessary tests to reduce the chance of a lawsuit for negligence) and the fee-for-service system (paying physicians for each episode of care), with its powerful financial incentives to do more, contribute to our culture of excess. However, the fact remains that a huge amount of excess care results from profligate practice styles.

This is something doctors often do not wish to admit. A poll in 2013 revealed that most doctors deny “major responsibility” for cutting costs. Yet those denials fly in the face of the evidence. The fee-for-service system does not account for the high rate of unnecessary surgery at many hospitals where the surgeons are paid a salary and have no financial incentive to provide unnecessary treatment. External factors do not explain the common tendencies to obtain multiple imaging studies of the same organ when one would suffice, to obtain blood tests of hospitalized patients far more often than necessary, to overuse antibiotics and screening tests, or to provide so many unnecessary CT scans and back surgeries.

The great majority of medical expenditures are under the control of physicians; no one forces doctors to order or do anything. The fact that profligate medical practice is not the only cause of excessive care and soaring costs does not lessen its significance. America is one of the countries that pays the most for healthcare in the whole world. If we are going to fix that, doctors need to be part of the solution.