Nashville, Tenn.-based Ardent Health Services said an unauthorized actor extracted copies of documents containing patient information from its organization and affiliates during a Nov. 23 ransomware attack.
According to a Jan. 22 update from Ardent's website, certain individuals' personal information was compromised during the attack and its data review process is "ongoing."
Ardent began mailing letters to those affected Jan. 22, but did not disclose how many patients were affected or what kinds of information was compromised.
UT Health Tyler, in Texas, was among the affiliates whose patient information was breached as a result of the attack on Ardent, according to news outlet Tyler Morning Telegraph.
Ardent says it has no indication that the compromised information has been misused.
The health system owns and operates 30 hospitals and more than 200 sites of care.