The made-in-Minnesota innovation of small clinics in stores caring for a limited set of ailments might not save the health care system much money.

Backers of retail clinics have long argued that the centers produce savings, since they charge less than an emergency room or traditional clinic when caring for things like a sinus infection or earache.

That's true, according to a study released Monday, but overall costs for low-severity illnesses are higher among patients who get treatment at retail clinics. That's probably because with added convenience, patients seek help for small problems they'd otherwise suffer through on their own.

"If the retail clinic weren't there, the person who wakes up with the earache might take an Advil or something to deal with the pain," said J. Scott Ashwood of Rand Corp., a nonprofit research group. He added: "The net impact on spending is actually a slight increase."

Retail clinic providers challenged RAND's study, saying it doesn't reflect the value the centers provide as a source of care for people who otherwise wouldn't get it.

As health insurance coverage expands with the federal Affordable Care Act, retail clinics are providing an important source of care for people who've lacked a regular provider, said Dr. Andrew Sussman, president of MinuteClinic, which is owned by Rhode Island-based CVS Health Corp. The upfront care can prevent downstream health problems that are much more costly to treat, and aren't measured by the study, Sussman said in a statement.

The extra spending on low-severity illness that's documented in the study is tiny in the context of overall health costs, said Tine Hansen-Turton, executive director of Convenient Care Association, a trade group. The data used in the study is old and "fails to capture current retail clinic visits for prevention, wellness and chronic disease, which can decrease overall costs," Hansen-Turton said in a statement.

The first retail clinic opened in May 2000 at a Cub Foods store in St. Louis Park, said Tom Charland of Merchant Medicine LLC, a Shoreview-based consultant that tracks the industry. The company that opened the first outlet eventually became known as MinuteClinic, the Minneapolis-based firm acquired by CVS in 2006 for $170 million.

As of January, CVS was the largest operator of retail clinics with 1,041, according to Merchant Medicine, followed by 403 clinics at pharmacy giant Walgreens. Big box retailers Target and Wal-Mart have made forays into the retail clinic business over the years, and a growing number of traditional health care systems including Rochester-based Mayo Clinic are giving it a try.

Currently, there are about 2,000 retail clinics across the U.S. receiving more than 6 million patient visits annually.

To study the cost impact, researchers looked at data from a large health insurance company operating in 22 U.S. cities, including Minneapolis, between 2010 and 2012. They focused on 11 conditions, including sore throats and upper respiratory infections, that account for more than 60 percent of visits to retail clinics.

Researchers wanted to see if retail clinic users were, in fact, substituting the lower-cost source of care for treatment by ERs and traditional clinics for low-intensity conditions. They also wanted to see if access to retail clinics was driving new uses, as well.

By comparing data from retail clinic users with those who didn't seek care in a storefront, researchers found both things were true. Per-person spending on low-severity illness at ERs and traditional clinics dropped by $21 per year, researchers found, among those who visited retail clinics. But spending on these ailments at the retail clinics increased by $35 — for an overall increase of $14 per person per year.

"The increased spending from new utilization outweighs the savings from substitution," researchers wrote.

Whether this is a good thing or a bad thing depends on your perspective, said Ashwood.

Patients likely gained value from the new utilization, particularly those who otherwise lacked a source for care. Insurers, however, could see things differently since "health issues addressed at retail clinics are typically self-limited, and therefore a visit may not improve health in the long term," researchers wrote.

Given the study results, insurers might want to reconsider any incentives like waiving co-payments for patients treated in retail clinics, said Dr. Ateev Mehrotra, a Harvard Medical School researcher who contributed to the study. "If the goal is to lower costs, then encouraging use of retail clinics may not be a successful strategy," he said in a statement.

But Dr. Robert Stroebel, a primary care physician at the Mayo Clinic, said the study didn't account for one key potential benefit of retail clinics: patients with less severe problems who are cared for there create space at traditional clinics for more complex patients. "Even if we're adding a little bit of cost at the low end," he said, "I think we're adding value in the sense that we're improving the patient experience and we're potentially improving the overall quality of care."

Christopher Snowbeck • 612-673-4744 •

Twitter: @chrissnowbeck