Patients with back pain, headaches and upper respiratory infections are more likely to receive low-value care at hospital-based primary care clinics than at community-based primary care clinics.

Those were the findings of a new study published in JAMA Internal Medicine.

Providers at hospital-based clinics were shown to refer too many patients to specialists and order too many CT, MR and X-ray exams. This brings into question the value of care that is delivered in these settings.

Researchers at Harvard Medical School and David Geffen School of Medicine at UCLA compared the records of 31,000 appointments over a 17-year period from two national databases. They excluded patients with complex symptoms that suggested serious disorders.

They found that the hospital-based clinics and community-based clinics prescribed antibiotics at about the same rate. But those who visited hospital clinics were referred for MR and CT exams more than those who went to community clinics — 8 percent and 6 percent, respectively.

Thirteen percent of hospital-based clinic patients were referred for X-rays compared to 9 percent for community-based clinic patients. The biggest difference involved those evaluated by a specialist — 19 percent versus about 8 percent, respectively.

Dr. John Mafi, the study’s lead author and physician at UCLA, speculated that physicians working in hospitals may be more likely to refer patients for those imaging procedures because they’re more immediately accessible and convenient.

Mafi and his team concluded that the key factor driving the disparity is the location of the clinic rather than whether the clinic is owned by a hospital or physician. Besides referring patients to specialists more often, hospital-owned clinics delivered similar quality care to physician-owned clinics.

“An estimated one-third of health care spending in the United States stems from services that provide low-value care,” Mafi said in a statement. “Reducing the use of such services can not only help curb health care costs — and redirect such resources in more meaningful ways — but it can also protect patients from the potentially harmful effects associated with them.”

The patients who were most likely to receive unnecessary tests and services were those visiting hospital-based primary care clinics and seeing someone other than their usual physician. That shows that patients may be over-tested when they jump from physician to physician.

“Not seeing your regular primary care physician — what we call discontinuity of care — might be a weak spot where low-value care can creep in,” Dr. Bruce Landon, the study’s senior author and professor at Harvard Medical School, said in a statement. “The more we know about what situations are most likely to lead to patients receiving low-value care, the more we can do to prevent it.”