Electronic health record (EHR)

An electronic health record (EHR) is the digital record of a patient's health information — diagnoses, medications, lab results, procedures, and clinical notes — maintained over time and, ideally, shared across the providers who treat that patient. It replaces the paper chart as the primary system of record inside a hospital or clinic.

EHR is sometimes used interchangeably with electronic medical record (EMR), but the terms differ: an EMR is typically a single provider's internal chart, while an EHR is designed to be interoperable and follow the patient across organizations. In practice, most vendor systems now blend both functions, and standards such as FHIR (Fast Healthcare Interoperability Resources) exist specifically to let EHR data move between systems.

EHR data is the primary raw material for population health management, clinical decision support alerts, and a large share of real-world evidence research, since it captures diagnoses and treatments as they actually occurred rather than as reported after the fact. For analytics teams, the main pitfalls are data entered inconsistently across clinicians, diagnosis codes used for billing convenience rather than clinical accuracy, and fields that go stale when a patient is seen elsewhere. EHR data also carries strict privacy obligations, commonly HIPAA in the United States, that govern how it can be used and shared.