Though accurate data is lacking, the overuse of services in health care probably cost hundreds of billions of dollars last year, out of the more than $2 trillion that Americans spent on health.

Are we getting our money’s worth? Not according to the usual measures of public health. The United States ranks 45th in life expectancy, behind Bosnia and Jordan; near last, compared with other developed countries, in infant mortality; and in last place, according to the Commonwealth Fund, a health-care research group, among major industrialized countries in health-care quality, access and efficiency.

And in the United States, regions that spend the most on health care appear to have higher mortality rates than regions that spend the least, perhaps because of increased hospitalization rates that result in more life-threatening errors and infections. It has been estimated that if the entire country spent the same as the lowest spending regions, the Medicare program alone could save about $40 billion a year.

Overutilization is driven by many factors  “defensive” medicine by doctors trying to avoid lawsuits; patients’ demands; a pervading belief among doctors and patients that newer, more expensive technology is better.

The most important factor, however, may be the perverse financial incentives of our current system.

Doctors are usually reimbursed for whatever they bill. As reimbursement rates have declined in recent years, most doctors have adapted by increasing the quantity of services. If you cut the amount of air you take in per breath, the only way to maintain ventilation is to breathe faster.