Nurse and busy mom-on-the-go Georgette Oosting, 31, doesn't get sick often, but when she does, you won't find her in the doctor's office. Instead, the Angie's List member of Midland Park, N.J., goes to MinuteClinic in CVS/pharmacy — one of about 450 MinuteClinics and 1,200 total retail health care clinics in more than 30 states nationwide that treat minor illnesses and injuries.

She's gone there for everything from strep throat to a urinary tract infection. "It's fast, easy and they're open the weird hours we can go," says Oosting, whose husband Rudi recently got a flu shot at the clinic. The couple's $30 copay is the same whether they visit a clinic, urgent care center or family doctor's office.

As the health care market broadens, people seeking medical treatment are increasingly more likely to have these three options, and the ER, close at hand. While 87 percent of respondents to an online Angie's List poll say they go to the doctor's office most often when health issues arise — "to ensure I get top-notch care," says member Teri Pote of Alexandria, Va. — 28 percent, including Pote, say they've visited a retail clinic.

Growth in the retail clinic sector has slowed in recent years, with some clinics shuttered. But the industry that took root in 2000 looks poised for another wave of expansion that could redefine its role in primary care.

Apart from convenience, many consumers choose retail clinics, primarily operated by CVS/pharmacy and Walgreens, because of cost. According to a 2009 study published in the Annals of Internal Medicine and led by Dr. Ateev Mehrotra, a researcher with RAND Corp., retail clinics treated three common conditions — sore throat, earache and urinary tract infection — for substantially lower average costs than urgent care centers, primary care providers or emergency rooms.

The costs reflect differences in plan reimbursement levels, which account for everything from doctors' salaries compared with nurse practitioners and physician assistants who generally staff retail clinics, to expensive diagnostic equipment. "Our main goal in the ER is to rule out life-threatening emergencies," says Dr. Anthony Cardillo, an emergency physician at highly rated Glendale Adventist Medical Center in Glendale, Calif. "That can lead to exhaustive work-ups."

Besides a lower sticker price upfront, which is attractive to those without insurance and millions more with high deductible plans, retail clinics are increasingly covered by insurers. Copays vary but are often comparable to other primary care settings, typically $10 to $30; a copay for the emergency department can range from $50 to $200 — an attempt to dissuade people from going to the ER for non-emergency problems, says Dr. Bruce Hochstadt of New York-based human resources and benefits consulting firm Mercer.

There are other reasons retail clinics are forecasting increased traffic. Because of an insurance mandate in the new health care law, about 32 million more people are expected to get health insurance by 2014. "There's going to be more demand [and at least initially] the same number of docs," Mehrotra says. That's expected to push people to alternative care settings.

Mehrotra's research also shows that retail clinics are comparable to urgent care centers and physicians' offices on measures of quality and fare better than emergency departments. His team reached these conclusions after examining 14 quality indicators, such as what kind of tests were ordered and what drugs were prescribed. They determined that one in five visits to a doctor and one in 10 to an ER could be handled by a retail clinic.

Beyond just treating ear infections and other common ailments, many retail clinics are now expanding their offerings to include injections for osteoporosis; diabetes monitoring, including blood glucose checks; and other chronic disease management. Hospital systems are moving to open convenient care clinics inside Walmart stores in smaller and larger markets. Rural areas represent a new frontier for the sector where options for primary care are often limited, says Tom Charland, an analyst who heads the Shoreview, Minn.,-based consulting and research firm Merchant Medicine.

"It's almost like the retail clinics are going to come out of the closet and say 'We're willing to be your medical home,'" Charland says. He believes they'll stop short of offering all services a primary care doctor would, in part, because their business model is built around speedy service — the top reason respondents to our poll say they go to retail clinics.

Still, some patients are already treating the clinics as an adjunct medical home in place of the family doctor. About 40 percent of those who visit retail clinics don't have a primary care doctor, according to Tine Hansen-Turton, executive director of the Convenient Care Association, a trade organization.

This concerns physician groups that say medical problems could be missed without an ongoing relationship with a primary care provider, or if patients regularly bypass the doctor's office in favor of a retail clinic. "You put a lot pressure on the patient to determine what level of care they need," says Dr. Roland A. Goertz, president of the American Academy of Family Physicians.

Georgette goes to an ob-gyn annually, but neither she nor Rudi has a family doctor. "Sometimes I wish we had a regular doctor who really knew us," Georgette says, but she doesn't see it as a pressing need. "I guess when we're old and need lots of medicine, we'll go."

MinuteClinic practitioners give patients who don't have a primary care doctor a list of doctors in their area accepting new patients. Practitioners provide the doctors of those who do with a visit summary. "We're not trying to displace the primary care provider, but really be complementary," says Paulette Thabault, chief nurse practitioner officer for MinuteClinic, which is headquartered in Woonsocket, R.I.

Still, member Lisa Kearns of Monroe, N.C., says it's worth paying her plan's higher $30 copay to go to a retail clinic or urgent care center versus $15 to see a primary care doctor. Given long waits for primary care physicians in the past, she's taken a particularly stark position: "Unless it were something serious like H1N1, I would never go to a regular doctor's office."