California Health Care Data

California Office of Statewide Health Planning & Development (OSHPD)

Clinical care and patient records data from licensed general acute care hospitals, emergency departments, and ambulatory care surgery centers in California. Includes inpatient discharge and outpatient encounter information.

Unit of Observation:
Personally Identifiable Information Available for Linking:
California, United States of America
Years Available:
Confidential: 2005 – present, certain files available since 1983
Frequency of Updates:
Annually by Mid-July

Encounter visit records from licensed general acute care hospitals, emergency departments, and ambulatory care surgery centers in CA. Many facilities that are called ambulatory surgery centers are not required to be licensed as surgical clinics, and do not report data to OSHPD.


OSHPD maintains two privacy levels of data files, and these privacy levels determine the availability of data and access procedures.

Publicly Available Data are available for free through the OSHPD Data & Reports page and through the CHHS Open Data Portal

Confidential Patient-level Data Sets are available for free to researchers associated with nonprofit educational institutions and to state agencies. OSHPD will not release Social Security number and does not list other identifiers in the data documentation. Eligible researchers must request the data through OSHPD and obtain approval for their research protocol from the state Internal Review Board for the California Health and Human Services Agency, also known as the Committee for the Protection of Human Subjects (CPHS). The Research Data Set Request process, including all necessary forms, is detailed here.

Research Datasets are restricted to “minimum variables necessary”. OSHPD links patient data to birth and death certificate data, but the linked data files are only available to qualified researchers through requests submitted to OSHPD and must be reviewed by the California Department of Public Health Vital Statistics Advisory Committee.

Timeline for Access

For university researchers, it takes approximately 6-9 months to receive confidential patient-level datasets after submitting a request, dependent on corrections needed.

Lag Time

Patient level data is generally available annually by Mid-July for eligible requestors. Linked birth data is current through 2012. Linked death is current through 2013. 


OSHPD no longer charges for patient-level data sets ordered or filled on or after 7/1/2018 for eligible requestors. This includes data sets for Patient Discharge Data sets (PDD), Emergency Department Data (EDD) and Ambulatory Surgery Center Data (ASD) for eligible requests for Limited Data Sets (formerly AB2876) and Research Request (formerly IPA) processes.  There are no refunds for data requests fulfilled prior to midnight on 6/30/2018. 


Researchers may request data for all records, or a subset of records (e.g. geographic area, diagnosis). It is unknown whether OSHPD will match records to a list of study participants.

When linking to outside data sources is necessary, OSHPD says, “Details of how the linkage can occur without the identifiers being released to the researcher need to be discussed. For example, you could track 'Patient A' but not actually know who this person is.”

Identifiers Available for Linking

  • Social Security number
  • OSHPD confidential data patient identifiers include:
  • Social Security Number
  • Date of birth

Linking to Outside Data Sources

Researchers must request permission from OSHPD for linking patient-level data across years/data sets. OSHPD requires this information even if the researcher is just linking within/between OSHPD data sets.

OSHPD records linked with California’s Vital Statistics Birth Statistical Master File, Birth Cohort File, and Death Statistical Master Files are also available for request through OSHPD.

Data Contents

The three main files provided by OSHPD are Patient Discharge Data (PDD), Emergency Data (ED) and Ambulatory Surgery Data (AS). For a full list of variables, see OHSPD's Data Documentation Page, which hosts an excel file of the Patient Data Master Variable Grid, 2018 PDD Data Dictionary, and 2018 ED/AS Data Dictionary.

Partial List of Variables

Patient discharge data, race/ethnicity, gender, emergency department data, patient demographics, diagnosis codes, MS-DRG, ICD-9, ICD-10, admission dates, discharge dates, hospital identifiers, payer information, clinical information, ambulatory surgery center data, outcomes related to Coronary Artery Bypass Graft (CABG)

J-PAL Randomized Evaluations Using this Data Set


Other Research Using this Data Set

Pollack, Craig E., Shawn Du, Amanda L. Blackford, and Bradley Herring. 2019. “Experiment to Decrease Neighborhood Poverty had Limited Effects on Emergency Department Use.” Health Affairs 38(1): 1442-1450. doi: 10.1377/hlthaff.2019.00452.

Last reviewed