Electronic Health Record (EHR) data is information pulled from a patient’s or patients’ digital medical record(s). That data can be analyzed with identifiable Protected Health Information (PHI), or after it has been deidentified. There is also an intermediate state called a limited dataset, in which some identifiers have been removed but dates, ages, and zip codes have been retained. There are different requirements for access and IRB approval depending on whether the data is identified, deidentified, or limited. EHR Data presents unique challenges for analysis as it was not collected originally for research purposes and typically entails extensive cleaning to be made useful for analysis. Epic is the largest vendor of EHR systems, with approximately one-third of the market.
A systematic review on EHR data in population health research: https://pubmed.ncbi.nlm.nih.gov/30269237/