CCW Frequently Asked Questions (FAQ)
What is the Chronic Condition Data Warehouse and why did CMS create the CCW?
How were the algorithms defined?
What are the source articles for the algorithms?
What if I want to modify the algorithms?
How is the CCW data different than CMS's standard 5% sample data?
How can I make national estimates using the CCW 5% plus sample?
Which data files are included in the CCW data?
How do I link existing CMS 5% files with the CCW data?
How are the assessments linked to the claims data?
How much do the data files cost?
What is the Chronic Condition Data Warehouse and why did CMS create the CCW?
One of the goals of Section 723 of the Medicare Prescription Drug, Improvement, and Modernization Act of 2003 is to make Medicare data readily available to researchers who are studying chronic illness in the Medicare population. To support this effort, the Centers for Medicare & Medicaid Services (CMS) awarded a contract to establish the Chronic Condition Data Warehouse (CCW). The CCW contains existing CMS beneficiary data (from multiple data sources) linked by a unique, randomly assigned identifier, allowing researchers to analyze information across the continuum of care.
The intended use of the CCW data is to identify areas for improving the quality of care provided to chronically ill Medicare beneficiaries, reduce program spending, and make current Medicare data more readily available to researchers studying chronic illness in the Medicare population.
How were the algorithms defined?
The specific chronic condition cohorts were defined by CMS, in collaboration with the Research Data Assistance Center (ResDAC) and the CCW contractor. For specifics on the algorithms, please see Attachment A of the User Manual for the exact definition.
What are the source articles for the algorithms?
Please see the CCW Algorithm Reference List that contains the source algorithm articles.
What if I want to modify the algorithms?
CCW allows researchers to customize the data request by specifying the changes on the Specifications Worksheet in the research identifiable data request packet.
How is the CCW data different than CMS's standard 5% sample data?
Please see the ResDAC technical publication titled "Differences in How the Medicare 5% Files are Generated".
How can I make national estimates using the CCW 5% plus sample?
Since the CCW is an ever enrolled 5% data file, in order to extrapolate results to obtain a national estimate, the researcher will need to refer to the Beneficiary Summary File included in the request. This file contains a flag that indicates whether a beneficiary was included in the CMS 5% sample for the year (i.e., the cross-sectional annual sample) or if the beneficiary was included as a member of the CCW Enhanced 5% sample (i.e., all inclusive, ever enrolled sample). The CMS 5% annual sample can be multiplied by 20 to extrapolate results to obtain a national estimate.
Which data files are included in the CCW data?
The CCW contains various types of CMS data from multiple care settings. This includes Medicare Institutional (Inpatient, Outpatient, Skilled Nursing Facility, Home Health Care, Hospice) and Non-institutional claims (Carrier, Durable Medical Equipment), assessment (Minimum Data Set, Outcome and Assessment Information Set, Inpatient Rehab Facilities Patient Assessment Instrument, and Swing Beds), and Medicare enrollment and eligibility data (CCW Beneficiary Summary File), and Chronic Conditions (CCW Chronic Conditions Summary File). For a complete list, please go to the CCW User Manual.
How do I link existing CMS 5% files with the CCW data?
What if I currently have CMS's standard 5% sample files and want to link to the CCW files? Can I link these data?
If a researcher previously received the 5% sample files from CMS and would like to use the Chronic Conditions Summary File from CCW, the researcher would need to submit a research identifiable data request to CMS requesting the specific CCW data files and the CCW beneficiary id to the RDDC beneficiary id crosswalk file. This will allow the researcher to link the existing CMS 5% sample files with the CCW data.
How are the assessments linked to the claims data?
CCW assessments and claims are linked using the CMS Enterprise Cross Reference (ECR) process. The CMS ECR process uses beneficiary identifiers such as name, address, date of birth, and gender to match a person across files. Each of the variables is weighted differently and a confidence score is calculated based on the variables that match. CMS has determined a confidence score threshold that will determine which match is considered valid. The assessment data and the claims data are linked using the ECR process, which means that researchers do not need to request SSNs and HICs from the assessment data in order to link to the claims data.
How much do the data files cost?
CMS policy prevents posting the Identifiable File prices on the web. Broadly, the cost of the data files vary by the number of chronic conditions selected, the file type, and the number of years requested. However, to give researchers a ballpark idea of the costs of these data, if you requested all Medicare utilization, enrollment, assessments, and chronic conditions summary file for the entire Chronic Conditions Data Warehouse for a known cohort or a random 5% sample of the Medicare population, it would cost approximately $11,000-$15,000 per year. To obtain a formal CMS CCW cost estimate please complete the cost estimate form and e-mail it to resdac@umn.edu.
Last Modified October 16, 2008