The greatest medical resource you've never heard of: Rochester epidemiology project

It's the medical resource behind discoveries that have affected patients around the globe, treasured by researchers and funded by the National Institutes of Health for nearly 50 years: the Rochester Epidemiology Project. This comprehensive medical records pool makes Olmsted County, Minn., one of the few places in the world where scientists can study virtually an entire geographic population to identify trends in disease, evaluate treatments and find factors that put people at risk for illness — or protect them. And, as it nears the half-century mark, the project is still growing. Health care providers in seven southeastern Minnesota counties are adding patients' records, including Dodge, Fillmore, Goodhue, Houston, Mower, Wabasha and Winona, more than doubling the number of area residents included.

The project has followed a half-million lives since it began. Co-directors Walter Rocca, M.D., a Mayo Clinic neurologist and epidemiologist, and Barbara Yawn, M.D., research director at Olmsted Medical Center, describe how it developed and where it is going in this month's Mayo Clinic Proceedings.

"The Rochester Epidemiology Project is unique, especially because of its historical capability. We go back to 1966, and we can look at big chunks of histories of people's lives," Dr. Rocca says. "It's extremely valuable to be able to answer medical questions that have to do with prevention, better care and also with understanding the cost and the effectiveness of our interventions."

The project has supported more than 2,000 studies. Research making headlines in recent years includes the findings that women who had their ovaries removed before menopause are at higher risk of dementia; multiple exposures to anesthesia before age 3 are linked to more than double the incidence of attention-deficit/hyperactivity disorder; skin cancer is up dramatically in people under 40, especially young women; smoke-free workplace laws save lives; mild cognitive impairment is more prevalent in older men than in older women; and traumatic brain injuries are likely more common than had been believed.

Fewer than 5 percent of Olmsted County's residents opt out. Those who take part can help science without getting poked and prodded or even meeting a researcher. The project can be used to study pretty much any condition; dozens of studies that otherwise wouldn't be possible are under way at any given time.

The biggest change the Rochester Epidemiology Project is seeing mirrors the nation's changing demographics. While whites of Northern European descent have long made up most of Olmsted County's population, a new wave of immigration means that 1 in 4 children isn't of European descent, Dr. Rocca says. Currently, researchers looking for ethnic differences in studies can compare their findings from the project with a much smaller group of ethnically diverse patients, to see whether there are differences or it's a moot point, he says.

The project has its origins in the earliest days of Mayo Clinic. Long before computers existed, Mayo archived patient medical records, believing they would someday prove valuable to researchers. In 1966, Mayo obtained NIH funding to link medical records from health care providers across the county, including Olmsted Medical Center and the Rochester Family Medicine Clinic, and the Rochester Epidemiology Project was born. Eventually technology caught up and the records were put on computer.