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
Free or Paid
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 and Reports page and through the CHHS Open Data Portal. No particular permissions are needed to access this data. 

Confidential Patient-level Data Sets are available to researchers associated with nonprofit educational institutions and to state agencies. OSHPD charges for each dataset accessed, with prices ranging from $500-600/year per dataset. OSHPD will not release Social Security numbers 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). It is recommended to work on the CPHS and OSHPD applications in tandem. The process is further detailed and all necessary forms can be accessed on the Research Data Request page

Research datasets are restricted to “minimum variables necessary”. OSHPD also provides datasets linked to birth or death certificate data. These data files are available to qualified researchers through requests submitted to OSHPD and 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, depending on corrections needed.

Lag Time

Patient Discharge Data (PDD) is available 1983 onwards and Emergency Department (ED) and Ambulatory Service (AS) data are available 2005 onwards. Patient level data (PDD, ED, and AS data) is generally available annually by mid-July for eligible requestors. Linked birth data is current through 2012. Linked death is current through 2013.   


Publicly available data are accessible for free.

Confidential patient-level datasets cost $500-600 per dataset for a year’s access. OSHPD can also provide linkages to non-OSHPD data sources. Linkage to one non-OSHPD source is $2,500 and each non-OSHPD source is $1000 per linkage.

As an exception, California hospitals, public health departments, and students who demonstrate that their project is tied directly to fulfillment of academic requirements (such as a thesis or dissertation) can access confidential patient-level datasets at no charge.

For more details, see OSHPD’s Data Pricing Policy.


Researchers may request data for all records, or a subset of records (e.g., geographic area, diagnosis). OSHPD data cannot be used to re-identify actual patients, and linking processes are a factor taken into consideration upon review of a researcher’s request for data. When it is necessary for a project, OSHPD notes that details for linking without identifiers being released to the researcher need to be discussed.

OSHPD staff will provide deterministic linkages to confidential OSHPD data for a fee (discussed above under “Cost”).

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

Identifiers Available for Linking

  • Zip code and county of residence
  • Date of birth
  • Social security number (this identifier can be used for matching, but will not be released to researchers)

Linking to Outside Data Sources

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

Data Contents

The three main files provided by OSHPD are Patient Discharge Data (PDD), Emergency Data (ED) and Ambulatory Surgery Data (AS). 

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).

For a full list of variables, see the OHSPD Data Documentation page, which hosts the Patient Data Master Variable Grid, and the PDD and ED/AS Data Dictionaries. 

J-PAL Randomized Evaluations Using this Data Set

Domurat, Richard, Isaac Menashe, and Wesley Yin. 2021. “The Role of Behavioral Frictions in Health Insurance Marketplace Enrollment and Risk: Evidence from a Field Experiment.” American Economic Review, 111(5): 1549-1579. doi: 10.1257/aer.20190823

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