If clinics in Minnesota want to be viewed as economical, here’s an easy solution: Keep your patients out of the ER.

A new state report finds that spending on total medical care for privately insured patients in Minnesota averaged $490 per member per month in 2016, a 3 percent increase from 2015.

But medical groups varied by 90 percent in their prices and 70 percent in the frequency with which their patients sought care. And the variation was most dramatic in emergency department visits. Even after factoring out the reality that some clinics have sicker populations, the study found that patients from some clinics were three times more likely to go to the ER than patients from other clinics.

Clinic doctors might not have direct influence over whether patients go to the emergency room, but they have indirect influence, said Julie Sonier, president of Minnesota Community Measurement, a nonprofit that ranks clinics by their quality and costs and released this week’s report. For example, she said, doctors can help patients keep their chronic illnesses in check and educate them about the kinds of ER visits that are avoidable.

The study compared the actual rate of ER usage with the predicted rate based on a clinic group’s patient population, and counted only ER visits that did not result in hospital admissions.

Patients using Scenic Rivers Health Services clinics in central and northern Minnesota for their primary care were 75 percent more likely than expected to make ER visits. Total cost of care for Scenic Rivers was $671 per patient per month, the report showed.

Meanwhile, the ER usage rate among patients of France Avenue Family Physicians in Edina was 22 percent lower than expected. Its patients cost only $405 each per month.

Rural medical groups tended to have patients with higher ER use and costs, the report found, but there were exceptions. Ortonville Area Health Services had a lower-than-average ER rate, because doctors offered more same-day appointments and the adjacent clinic and ER facilities posted signs with guidance for patients, said Dr. Allan Ross, a primary care provider.

“There are two doors to enter into the ER, and posted on those doors are large print posters … relaying what type of problems are appropriate for the ER and clinic,” he said.

The total-cost report is based on claims paid for the care of 1.5 million privately insured Minnesotans. It also compared clinic groups by how often their patients were admitted to hospitals and how much they spent on prescriptions providing at least 30-day supplies of medications.

Individual clinic group results are posted at mnhealthscores.org.

Sticker prices for common procedures also varied widely; some clinics received $4 on average for standard patient eye chart tests, while others received as much as $46. Average payments to clinics for X-rays varied from $26 to $201.

Mayo Clinic in Rochester continued to rank in the annual report as the most expensive — at $977 per patient per month. Mayo officials have supported the cost-of-care reporting project since it started four years ago, but have challenged the methodology that makes its Rochester clinic appear expensive.

Patients are assigned to clinic groups if they have received more than half of their primary care services from them in a given year. That could include costly patients who get primary care at Mayo only because they are traveling to Rochester for the treatment of complex diseases.