If you grow up near Dover, N.H., you’re three times more likely to have your tonsils removed than a child growing up near Bangor. But a Bangor-area child is 2.5 times more likely than a child in Lebanon, N.H., to receive an abdominal CT scan.

Those are among the conclusions of researchers from the Dartmouth Atlas Project in New Hampshire, who examined health insurance claims data for children in Maine, New Hampshire and Vermont to learn about the variability of children’s health care by region.

Their analysis confirmed a fact well known in the medical community: Certain routine procedures are more common in particular areas than others. Further, the reason isn’t because of greater medical need in one area than another. A region’s prevailing medical culture — not what the scientific evidence says is best practice — has a greater influence on how often doctors order particular procedures.

What do these insights add to the debate about health care in the U.S.? While limited access to care is genuinely a problem for some regions, the data point to the reality that many in the U.S. receive too much health care. Excessive care not only inflates spending; it can expose patients to unnecessary risks and side effects — such as radiation from excessive imaging.

The Institute of Medicine in 2012 estimated about 30 percent of health care spending in the U.S. — which reached $2.7 trillion in 2011pays for unneeded care that doesn’t improve patient health. In a 2011 survey published in the Archives of Internal Medicine, 42 percent of primary care physicians thought patients in their own practices received too much care.

Doctors — particularly specialists — can profit from providing excessive care, especially self-referrals. That’s when the referring physician performs the specialized test, procedure or surgery he or she recommends for his or her patient. And fee-for-service payment systems used by insurers reward health care providers for the quantity rather than quality of care.

Another driver for excessive care is “defensive medicine” — ordering that extra test, procedure or hospital readmission as a precaution to protect doctors from lawsuits. In a 2008 survey of Massachusetts doctors, 83 percent admitted to practicing defensive medicine. That study found 18 to 28 percent of tests, procedures and referrals were ordered to avoid lawsuits.

The United States’ per-capita health spending dwarfs that of its industrialized peers, without the improved outcomes to go along with it. Yet growth in health spending has slowed over the past three years to the slowest three-year growth rate on record.

The reasons why could hold some of the answers for how the nation can rein in its spending on unneeded care. Particularly, measures that hold health care providers accountable for their patients’ overall health — many of them included in the federal Affordable Care Act — should be applied more broadly.

Under the Affordable Care Act, for example, Medicare has started penalizing hospitals with high rates of patient readmissions within a month of being discharged. This not only directly lowers Medicare spending. It provides hospitals with an incentive to improve the quality of care.

The Affordable Care Act also has accelerated a shift toward accountable care in which health care providers are paid to keep patients healthy and out of the hospital rather than for each test and procedure performed. That model shows promise as a way to cut back on unnecessary health care.

However, even as payment reform makes a difference, the threat of litigation remains for care providers. Thus, the incentive remains to practice defensive medicine considered unnecessary from a medical standpoint.

States could consider changing their medical malpractice laws to incorporate national standards of medical practice determined by the dozens of professional medical societies to be most effective in improving patient health. Such an approach could defend doctors who follow what the evidence tells them is right for the sake of the patient, not for the sake of legal defense.

And there’s more the federal government can do without new laws. The Affordable Care Act includes consequences for hospitals — the loss of their tax-exempt status — that don’t aggressively inform eligible patients that they might qualify for financial assistance. The law also bars hospitals from charging these patients above-average prices, and it requires hospitals to publish lists of their traditionally opaque standard charges.

The Obama administration has dragged its feet in writing the regulations needed to implement these provisions. There’s no excuse for delaying these measures, which could prevent overcharging those least able to pay and make hospital charges more transparent.