As in-store health clinics continue to expand in the Pittsburgh market, research is raising concerns about their long-term viability.

Featuring upfront, no-frills menus limited to routine needs, retail clinics embrace a 15-minute, fast-food approach to health care that has gained in popularity.

Since the first such clinics opened here two years ago, the number has grown. The Pittsburgh area is expected to have 24 retail clinics by the end of the year, almost evenly divided between Take Care centers at Walgreens and MinuteClinics at CVS.

The first of the breed opened in a Minneapolis discount supermarket in 2000, founded by a father tired of long waits in urgent-care centers. Today, the MinuteClinic chain now owned by CVS/Caremark Corp. operates 500-plus clinics nationwide. It's the leader in a niche industry that comprises nearly 1,100 clinics tucked away in drugstores, department stores such as Target and Wal-Mart, plus supermarkets such as Publix, Shop 'n Save and Kroger's.

As one of the newer wrinkles in health-care delivery, so-called convenience clinics staffed by nurse practitioners have drawn the interest of researchers who have begun to explore how the clinics might be tilting the scales of care and costs.

At $104, a trip to a MinuteClinic in Minneapolis was about $50 less than one for the same care at a doctor's office or urgent care center and $279 less than an emergency room, according to a study in the September 2008 Health Affairs journal.

The 2003-2006 review was the first to compare the total cost, including not just the medical exam but also lab and pharmacy charges.

"The retail clinic emphasis on access, convenience and cost is clearly addressing needs that the rest of the care system does not yet fully meet," concluded lead author Dr. Marcus Thygeson of HealthPartners, a leading health care insurer and provider in the Twin Cities region.

Still, plenty of questions persist on both the medical and business fronts. In the last 12 months, 10 operators comprising 136 clinics have closed their doors, industry estimates show.

And roughly two-thirds of respondents in a 2007 Harris Poll were concerned about staff qualifications and the ability to diagnose serious medical problems at retail clinics, according to a California Health Care Foundation study in 2007, "Health Care in the Express Lane."

The HealthPartners study, meanwhile, found little evidence that clinics reduced costs to the health-care insurer overall, which for the easy-to-treat conditions studied rose by 14.1 percent. The average, per-episode cost rose 20.3 percent in the emergency room setting, 12.7 percent in the office, 11.9 percent at the urgent care and 12.2 percent at the MinuteClinic.

Adopting a wait-and-see attitude, Dr. Terence Starz, then president of the Allegheny County Medical Society, wrote in November of his concerns. "In a setting where a physician is not present to examine patients, there is a risk of an inaccurate diagnosis or of missing a serious medical condition. Seemingly simple cases aren't simple," the UPMC rheumatologist wrote.

"Are grocery stores and pharmacies the environments in which patients want to have their future health care delivered," he wondered, "or is this movement an indication of a declining state of access to quality health-care delivery?"

Sandy Ryan, chief nurse practitioner officer for the Conshohocken, Montgomery County-based Take Care, countered that by at least one common industry metric, The Healthcare Effectiveness Data and Information Set, her clinics had proven their quality-of-care mettle.

"We consistently score above national standards on monitor tracking," she said of marks at or above 90 percent. "Our quality scores have been fabulous."

Despite an overall endorsement, the HealthPartners study and another led by UPMC internist Dr. Ateev Mehrotra acknowledged that several key issues were ripe for further research -- assessing the quality of care given the absence of a physician, for instance, and whether the cost savings merely shift the burden onto primary care physicians who see fewer and sicker patients.

The American Medical Association and others, Dr. Mehrotra wrote, "have raised concerns about whether health professionals operating at these sites make accurate diagnoses and appropriate triage decisions, and whether retail clinics potentially disrupt existing physician-patient relationships."

Dr. Mehrotra, in his September 2008 study for the Rand Institute where he is a research analyst, found that nurse practitioners are well-equipped to handle the 10 easy-to-treat needs that account for 93 percent of clinic patients -- upper respiratory problems, ear and throat infections, pink eye and so on.

"I think that's important to say, that these are relatively simple, acute problems like getting a flu shot," he said. "Pretty straightforward stuff."

His research, based on some 1.3 million clinic visits from 2000 to 2007, also referred to the surprisingly high 18 percent of patients who go to their doctors and 12 percents to ERs when they could have gone at less expense to a retail clinic.

Clinic visitors tend to be younger, healthy adults, two-thirds of whom don't have a family doctor and one-third of whom don't have insurance, the Rand study said, thus making the upfront fees more attractive.

"For these patients," Dr. Mehrotra said, "the convenience offered by retail clinics may be more important than the continuity provided by a personal physician."

While the Rand study focused on patient types and the HealthPartners study more on costs, a 2007 California Health Care Foundation study traced how the industry has grown, retrenched and taken off again.

Mary Kate Scott, a trade consultant who authored the "Express Lane" study, said clinics such as Take Care reflect the evolving, predominant business model.

Once an independent company using space in Rite Aid/Eckerd stores, Take Care has since been acquired by Walgreens. It has expanded its footprint as well as range of patient and workplace services.

But like others, what intrigues her the most is the trend toward traditional health-care providers getting into the business, a form of vertical integration.

That's what has happened at HealthPartners and closer to home at the Geisinger Health System in Danville, Montour County, where five CareWorks have been set up in Central Pennsylvania supermarkets.

Will UPMC be next, or maybe Giant Eagle?

"A lot of people look at Pennsylvania as being very interesting as a market," Ms. Scott said, thanks to Gov. Ed Rendell-led changes that have eased regulations covering nurse practitioners.

Tom Charland, CEO of Shore-view, Minn.-based Merchant Medicine consultants, said more than 100 retail clinics were operated by hospital systems under their own brand.

"I'm surprised we haven't seen any hospital systems in Pittsburgh or Philadelphia move into the market, but it's just a matter of time before they do."