The hospital data presented on Cal Hospital Compare is the result of a partnership among independent organizations dedicated to improving health care quality. IBM Watson Health provides data support and analysis. IBM Watson Health delivers unbiased information, analytic tools, benchmarks, and services to hospitals, government agencies, employers, health plans, clinicians, and pharmaceutical and medical device companies.
Data Sources
Cal Hospital Compare includes hospital measures for clinical care, patient safety, and patient experience for all acute care hospitals in the state of California with publicly available information. This does not include psychiatric hospitals, rehabilitation facilities, long-term acute care hospitals and specialty only hospitals. Some small, rural, or Critical Access Hospitals do not have publicly available data or a sufficient amount of data to score them accurately. Measures of children’s health care are not included nor widely available. The conditions and procedures rated are among the most common reasons for being admitted to a hospital.
California hospitals report their data to various federal and state agencies as noted below.
- California Department of Public Health (CDPH)
- California Maternal Quality Care Collaborative (CMQCC)
- California Joint Replacement Registry (CJRR)
- California Office of Statewide Health Planning and Development (OSHPD)
- CMS Hospital Compare
In all cases, we use the most recent data available. The time periods vary for different measures and can be found in the hospital profile page information popups.
Patient Experience
- CMS Hospital Compare
Mother & Baby
- Breastfeeding Rate: California Department of Public Health
Reporting Period: For the following Mother & Baby measures data represents Calendar Year 2018 performance for 213 hospitals. These hospitals submitted data to the CMQCC Maternal Data Center to enable rapid-cycle reporting and quality improvement. Twenty-two hospitals did not submit data to the CMQCC Maternal Data Center; their results represent 2017 data available from OSHPD. The hospitals that did not report 2018 performance data to CMQCC are listed here.
- Cesarean Birth Rate: CMQCC; 2018 rates based on Patient Discharge Data submitted by each hospital to the CMQCC Maternal Data Center* and linked to Birth Certificate Data from the California Department of Public Health-Vital Records. Performance categories developed by Cal Hospital Compare). Measure specifications: Joint Commission PC-02 (See Manual)
- Episiotomy Rate: CMQCC; based on Patient Discharge Data submitted by each hospital to the CMQCC Maternal Data Center*; Performance categories developed by Cal Hospital Compare. Measure specifications: National Quality Forum 0470 (See Measure Definition)
- VBAC Rate: CMQCC based on Patient Discharge Data submitted by each hospital to the CMQCC Maternal Data Center.* Performance categories developed by Cal Hospital Compare. Measure specifications: Agency for Healthcare Research and Quality Inpatient Quality Indicator (IQI) 34. (See Measure Definition)
- VBAC Routinely Available: Survey by Hospital Quality Institute (HQI) in 2016; updated by CMQCC based on hospital feedback in March 2019.
- Deliveries by Certified Nurse Midwives: CMQCC; 2018 and 2017 rates based on Birth Certificate Data from the California Department of Public Health-Vital Records.
Hip & Knee
- CMS Hospital Compare
- California Joint Replacement Registry
- OSHPD
Patient Safety
- CMS Hospital Compare
- OSHPD
Healthcare Acquired Infections (HAIs)
- CDPH
Cancer Surgery
- CDPH
- OSHPD
Emergency Department (ED) Care
- CMS Hospital Compare
Heart & Lung Conditions
- CMS Hospital Compare
- OSHPD
Surgeries/Other Conditions
- OSHPD
Stroke
- CMS Hospital Compare
About the Ratings & Data Sources
To produce the hospital information available on Cal Hospital Compare, a rigorous process is followed:
- Data are gathered by IBM Watson Health Analytics from publicly available sources.
- Data are then compared to a benchmark value, either a national, state, or Cal Hospital Compare standard.
- Ratings are assigned to measures when it is technically feasible (for example, a large enough sample or an accepted risk-adjustment approach) and there is an appropriate standard.
Guidelines established by a technical oversight committee and expert statisticians determine how the data are processed.
Risk-Adjustment Methods
Some patients respond better to treatment than others. For example, having diabetes can reduce your chances of surviving heart surgery. So it would not be fair for a hospital with more diabetic patients to have a worse rating just because they treat more sick patients. “Risk adjustment” is the process that levels the playing field among hospitals to fairly compare hospital performance.
Some measures do not need to be risk adjusted. For example, having diabetes does not prevent the nurse from checking your wristband before giving a medication, so there should be no adjustment for diabetes in that measure. The organizations providing the data determine whether risk adjustment is applied to the measures. In general, the effect of the risk-adjustment process on hospital scores is small.
Applying a Margin of Error to Data
Another way to make sure that fair comparisons can be made between different hospitals is to apply a “margin of error.” This helps compare hospitals that perform very few procedures with those that perform many. For example, a hospital that does only one heart surgery will have a death rate of either 0% (if the patient lives) or 100% (if the patient dies). Based on the outcome for one patient, it is difficult to determine how the hospital would perform for many surgeries on many patients. So we apply a wide margin of error that says the death rate is not very reliable because it is based on just one case.
For hospitals that have only a few patients with a particular condition, their margin of error in that condition is broad, while for hospitals with hundreds of patients the margin for error is narrow. For this reason, for any single measure on this site, two hospitals with the same rating may have very different percentages shown. In rating the hospitals, the margin of error is taken into account by calculating an estimated range of hospital performance for each condition, with the range wider for hospitals with fewer patients and narrower for hospitals with many patients.
Performance Ratings
The performance rating icons indicate how well a hospital performed compared with other hospitals. Depending on the type of measure, the scale will use all five (superior, above average, average, below average, and poor) or only three of these ratings (superior, average, and poor).
Case Volume Ratings
Research has shown that the more cases a hospital handles for a particular procedure, then the surgical team has more practice, which may lead to better results for the patients. This website provides case volume ratings for some surgical procedures. Hospitals are rated as either having “enough cases” or “not enough cases.” To determine the rating, the hospital reports the number of cases performed and it is compared to a specific “cut point” as determined by medical research. For hospitals that meet the cut point, the website also shows the risk-adjusted death rate for the procedure. For the cancer surgery volume data presented, no ratings or cut points are provided given that the medical research is not conclusive regarding an exact cut point.
