About OCHIN and OCHIN Data

OCHIN, a nonprofit health care innovation center with a core mission to advance health equity, operates the most comprehensive database on primary healthcare and outcomes of traditionally underserved patients in the United States1. The OCHIN Epic EHR data warehouse aggregates electronic health record (EHR) and social determinants of health (SDH) data representing >6 million patients from 170 health systems and 1,600 clinic sites across 33 states (4.6 million patients are ‘active,’ with a visit in the last 3 years). Approved AIM-AHEAD projects can obtain access to up to 11 years of longitudinal OCHIN Epic ambulatory EHR data, which is research-ready on the PCORnet Common Data Model (CDM).


Contributing health systems are outpatient community-based health centers (CHCs), which deliver comprehensive, culturally responsive, high-quality primary care health care services for communities most impacted by health disparities. This includes individuals and families experiencing poverty, houselessness, migrant agricultural workers and veterans2. CHCs often provide on-site services such as dental, pharmacy, mental health, substance abuse treatment, and social work regardless of patients’ ability to pay.

1OCHIN leads and is the largest data contributor of the ADVANCE Clinical Research Network (CRN), a member of PCORnet. (https://advancecollaborative.org/)

Explore the OCHIN Community Health Equity Database through Cohort Discovery, a web-based software tool for obtaining counts of patients matching user-specified inclusion/exclusion criteria. To gain access to Cohort Discovery, AIM-AHEAD program applicants must have completed and be up to date with standard training in Human Subjects Research and Responsible Conduct of Research. Access will be granted within 3 – 7 business days after the requester provides an appropriate public IP address for the network from which the requester will access Cohort Discovery

Overall Inclusion of Source Database
  • Data years available for AIM-AHEAD: 2012-2022 (>170 million total encounters)
  • Patients with one or more ambulatory, telehealth, or dental visit at a member clinic site on or after 1/1/2012
  • Records from institutionalized patients and neonates (<28 days old) are excluded


Key Characteristics of OCHIN EHR Data Percent Patient Count
Total all-time patients 6,009,798
100% and Below Federal Poverty Level (FPL) 55.0% 3,306,034
101% - to 200% FPL 15.4% 928,348 
Medicare 8.0% 482,055
Medicaid 47.5% 2,856,580
Uninsured 25.7% 1,545,991
Spanish Speaking 20.1% 1,209,433
Black 17.3% 1,038,841
Hispanic / Latino/a/x 32.4% 1,948,448
Asian 5.4% 324,851
American Indian/Alaska Native 1.0% 59,143
Diabetes1 11.4% 323,272
Hypertension1 21.7% 617,061
Asthma1 6.6% 187,197
Congestive Heart Failure 1.0% 49,377
Chronic Kidney Disease1 2.5% 70,808
Mental/Behavioral Health Dx1,2 26.1% 740,961
Obesity1,3 35.4% 1,006,685
1Chronic condition percentages presented among active adult patients (N=2,842,576)
2Includes anxiety, bipolar, depressive disorders, schizophrenia, and other psychotic disorders 
3Obesity diagnosis on problem list or last-recorded BMI >30
Available Data at a Glance
Domain Example variables
Demographics Sex, age, race, ethnicity, language, FPL, sexual orientation, gender identity, vital status/death date, state, and zip code of residence.
EncountersEncounter type, level of service, provider type, date.
Diagnoses (from encounters, problem list, and patient-reported medical history)ICD-9 and ICD-10 diagnosis codes, description, date.
Procedures (from encounters and patient-reported surgical history)CPT and HCPCS procedure codes, description, date.
VitalsBP, BMI, and tobacco use measurements, measurement date.
Laboratory resultsLab type (standardized to LOINC), specimen source, date, result.
Medications (prescribing and dispensing)RxNorm, NDC, medication name, dose, quantity, route, frequency, refill count.
Patient-reported outcomesScreening questionnaire responses (e.g., PHQ2, PHQ9, AUDIT), screening date.
ImmunizationsImmunization type, dose, administration date.
Social determinants of healthPatient-level social needs screenings recorded in EHR, e.g., food insecurity, housing quality, housing insecurity, transportation needs, education, employment.
Community vital signsGeographically linked neighborhood-level indicators at census tract and/or ZCTA level, primarily from the American Community Survey. Sample measures: median household income, educational attainment, employment rate, social vulnerability index.
OCHIN Patients by Clinic’s State
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