Roughly four million people who've used Advocate Medical Group doctors or services dating back to the 1990s may be at risk for identity theft after four computers were swiped last month.
The computers, inside a nondescript building in Park Ridge, northwest of Chicago, were stolen July 15, company officials said.
The computers didn't contain medical records but did hold patient information, including names, addresses, dates of birth, Social Security numbers and some clinical information such as treating physicians and department, diagnoses, medical record numbers, medical service codes and health insurance data, the company said in a release.
A company spokesman said law enforcement from Park Ridge was notified immediately after the heist.
Letters to patients began going out Friday, and those patients at risk will receive free credit monitoring and identity theft protection, the company said.
"Our number one focus right now are these patients," said Kelly Jo Golson, a company spokeswoman. "There's been no indication that this information was targeted, that these computers were targeted, no indication that this information has been used inappropriately."
The company said 24 hour security has since been placed at the building where the computers were stolen.
The medical group is the area's largest, with more than 1,100 physicians in more than 200 locations, including hospitals such as Advocate Christ Hospital in Oak Lawn and Advocate Lutheran General Hospital in Park Ridge. The company said only patients of Advocate Medical Group were affected.
“While we are keenly focused on the investigation and security enhancements, everyone’s efforts right now are concentrated on our affected patients,” Advocate Medical Group's Chief Medical Officer Kevin McCune said in a statement. “If one patient is impacted – that’s one too many."