Retail clinics have recently boomed in popularity. Visits to these clinics, often set up in shopping malls or drug stores, quadrupled between 2007 and 2009.

That's what we know for sure. What we know less about is what that means for the quality of American health care. On the one hand, these clinics increase access to health care services at a potentially lower price. On the other, doctor groups argue that the retail clinics will worsen care by disrupting the relationship between patients and physicians. 

New research from the RAND Corporation adds some helpful data to this debate. Their researchers find, in last week's Journal of General Internal Medicine, that retail clinics do disrupt the patient-provider relationship -- but not necessarily in a way that worsens health care.

The RAND researchers started by looking at where patients go when they have a new medical problem. Using that metric, they found that visits to retail clinics were associated with fewer trips to the primary care doctor to diagnose a new problem. Those who went to a retail clinic were also less likely to see their primary care doctor going forward.

"We saw about a 10 percent drop in people who had a primary care visit in the subsequent year, after a retail clinic visit," says Ateev Mehrotra, an associate professor of medicine at the University of Pittsburgh, and co-author of the study.  

Those two metrics showed a negative impact on primary care. But there's also a third metric Mehrotra and his colleagues used: Whether patients were getting the care they needed, regardless of who delivered it. They looked at whether diabetic patients were receiving the battery of recommended tests and, in the more general population, at rates of preventive screenings (things like breast cancer and cholesterol level tests).

When they looked at health care through this lens  they found no difference. It didn't matter whether a patient went to a retail clinic or a primary care doctor; they still go the same amount of preventive care. 

"I think there are questions about what we mean by continuity of care," says Mehrotra. 

One meaning could be just about the actual care delivered, the battery of tests that one is supposed to get at various points in their lives. On that metric, retail clinics look as if they're performing relatively well. 

Another meaning though could be about developing a relationship with a provider and having a specific individual who takes care of your health care needs, perhaps noticing at a routine exam if something seems amiss.

The open question from this paper seems to be whether that type of continuity of care, with a specific provider, is of value.