Los Angeles County Department of Health Services officials said appointment lists containing 743 patients' personal information were stolen in the breach after a hospital employee discovered their car had been broken into on July 8, according to NBC 4 news.
Information in the appointment lists included full names, birth dates, medical record numbers, phone numbers, genders, clinics and appointment information.
Patients' social security numbers and financial information were not included in the documents, according to the article.
The breach affected patients treated at the LA County+USC Neurosurgery Clinic between May 10 and July 26, according to the article.
The department of health services sent letters to patients affected by the breach and posted a notice to its website for patients whose mailing addresses were not immediately available.