ST. PAUL, Minn. (AP) — The Mayo Clinic’s treasure trove of medical records is getting even bigger.

Since 1966, Mayo has collected as many records as possible from Olmsted County and used them to generate important studies that help save lives. The Rochester Epidemiology Project now holds close to 600,000 medical records.

The project is now expanding to include patients from Mayo affiliates in seven other southeastern Minnesota counties, which will help researchers broaden the database, Minnesota Public Radio reported Monday (http://bit.ly/14iXEzP ). The counties are Dodge, Fillmore, Goodhue, Houston, Mower, Wabasha and Winona. The hospital-and-clinic system also has made contact with other regional providers outside of the Mayo system to see if they’re interested in participating.

Jennifer St. Sauver, scientific manager of the project, says having access to a large and growing pool of medical records gives researchers many more study options.

“The great thing about the Rochester Epidemiology Project is that it’s not confined just to one particular disease area or one particular condition,” she said. “Instead, since it’s just capturing all of the health care received by this local population, you can do studies of virtually any condition you can think of.”

The health data so far have generated more than 2,000 studies and provided groundbreaking information on a variety of conditions, including heart disease and attention deficit hyperactivity disorder. For example, researchers scanning the database found that heart attacks declined by 33 percent in Olmsted County after smoke-free workplace laws were implemented in 2002. Another study revealed that children who had multiple exposures to anesthesia before age 3 had an increased risk of ADHD. That research is ongoing.

“They’re following up that study now with a five-year grant to try and focus on understanding whether the anesthesia itself is a strong risk factor for later behavioral problems, or whether it’s the type of anesthesia or the dose or whether it’s other conditions that these children might have,” St. Sauver said.

Adding information from more patients in more counties will make the database even useful, she said.

“To do a study on, for example, pancreatic cancer in Olmsted County, just focusing on this population is hard to do because it’s a rare cancer and it just doesn’t affect enough people,” she said.

Mayo Clinic researchers also aim to improve racial diversity within the records pool. That would address a long-standing shortcoming of the database, as Olmsted County is predominantly white. In time, St. Sauver said, the demographics represented in the database will likely change as the region’s minority population grows.