Healthcare Information Division

Emergency Department and Ambulatory Surgery Data

An outpatient encounter record is submitted each time a patient is treated in a licensed emergency department or ambulatory surgery center in California.  These facilities report their encounter data via the Medical Information Reporting for California System (MIRCal). The reported data include patient demographic information, such as age, sex, county of residence, and race/ethnicity, diagnostic information, treatment information, disposition, and expected source of payment. County Frequencies for Emergency Department and Ambulatory Surgery outpatient encounters by patient county of residence can be downloaded below:

Emergency Department (ED) and Ambulatory Surgery (AS) Facility Summary Reports

ED and AS Facility Summary Reports are collected through MIRCal and may be accessed by data type, facility ID# or facility name and report period begin and end dates. Each report consists of a two-page summary which represents the number and percentage of each data element for a given facility.


Ambulatory Surgery Center Encounters, County Frequencies by Patient County of Residence
2005 | 2006 | 2007 | 2008 | 2009 | 2010 | 2011 | 2012 | 2013 | 2014

Emergency Department Encounters, County Frequencies by Patient County of Residence

2005 | 2006 | 2007 | 2008 | 2009 | 2010 | 2011 | 2012 | 2013 | 2014

ICD–9–CM Code Frequencies

CPT Code Frequencies


  1. Ambulatory Surgery (AS) – Top Ten Procedure Groups – 2014
  2. Emergency Department (ED) Encounters by Facility – 2014
  3. Emergency Department (ED) – Top Ten Cause of Injury - 2014
  4. Emergency Department (ED) – Top Ten Diagnoses and Diagnosis Groups - 2014
    • A statewide listing of the top ten principal diagnosis codes reported by Emergency Departments. Also included is a statewide listing of the principal diagnosis groups (based on ICD-9-CM codebook chapters). This data is only from ED encounters that did not result in a hospital admission.


Other Information

To order a Public Use File, see our Data Request Center

View information for Patient Discharge Data.

Attention Data Users: Please exercise caution when interpreting OSHPD data. The use of improper assumptions and analytical methods may result in erroneous or misleading conclusions. Conclusions drawn from OSHPD data are the sole responsibility of the user. Users should be aware that financial and utilization data products are based on a dynamic database that is constantly being updated. As a result, the same data item for a facility may change over time or be different between products.

If you are unable to download ZIP or EXE files, please e-mail the OSHPDWebmaster.
Extracted files can be e-mailed to users at no charge.

Page last revised: July 8, 2015 4:22 PM