OCHIN Research Data Warehouse

The OCHIN Research Data Warehouse (RDW) is a centralized research repository that houses clinical and administrative data for patients served across the OCHIN network, which operates a single, shared instance of the Epic electronic health record system. This architecture enables the creation of longitudinal patient records beginning in 2012 and hundreds of health systems and thousands of clinic sites, making the RDW well suited for health services, population‑based, and longitudinal research. The RDW as a single repository implements the PCORnet CDM and the OMOP data model. The RDW contains comprehensive EHR‑derived data—including ambulatory, inpatient, dental, and behavioral health information—as well as patient demographics, encounters, diagnoses, procedures, medications, laboratory results, and selected patient‑generated health data. Where appropriate approvals are in place, the RDW also supports linkage to external data sources such as external administrative and public datasets, Medicaid claims, and national mortality data using governed, privacy‑preserving methods. Researchers interested in using OCHIN data for approved research purposes may request access through OCHIN’s established research intake and review processes. Information about OCHIN’s research programs, data resources, and procedures for submitting a data request is publicly available on the OCHIN website. Data access is contingent on appropriate regulatory approvals and agreements, and the availability of specific data elements may vary by study. As of February, 2026 there are: 10,634,437 distinct patients over all time 7,510,731 distinct patients with a visit within the last 3 years Clinic sites in 43 states 293 health systems containing 2,696 clinics