Data Sources

The Pharmaceutical Economic Research (PER) group uses Centers for Medicare & Medicaid Service (CMS) research data from Chronic Conditions Data Warehouse (CCW). The CCW is a research database designed to make CMS research data more readily available. The CMS research data files are organized by data category including beneficiary enrollment and demographic files, medical claim files, Part D prescription medication claims and related Plan/Pharmacy/Prescriber characteristic files, and assessment files.

We have all the above enrollment, medical and pharmacy data files for the following population:

1. 5% random sample of Medicare beneficiaries 2006-2012 (over 2 million population each year)

2. 100% Medicare beneficiaries with a myocardial infarction 2008-2010

     a. Those with an MI in 2008 and followed up to 12/31/2009

     b. Those with an MI in 2009 and followed up to 12/31/2010

3. 100% Medicare beneficiaries with bipolar disorder, 2006-2009

4. 100% Medicare beneficiaries with schizophrenia, 2006-2009

5. 1% random sample of all prescribers who prescribed medications for more than 11 Medicare beneficiaries in 2009

For inquiries about using data, please contact Dr. Yuting Zhang.


Detailed Description of Data Files (with links to CCW data dictionaries)

1. Beneficiary Enrollment Files include Master Beneficiary Summary File; base, chronic condition, cost and use, and National Death Index (NDI) segment.

  • Base (A/B/D) segment includes beneficiary enrollment information, such as the beneficiary unique identifier, state and county codes, zip code, date of birth, date of death, sex, race, age, monthly entitlement indicators (A/B/D), reasons for entitlement, and monthly managed care indicators (yes/no).
  • Chronic Conditions segment includes 27 chronic condition data warehouse flags called CCW Flags. This includes 6 new chronic conditions in addition to the 21 chronic conditions previously defined.
  • Cost & Utilization segment includes summarized information about the service utilization and Medicare payment amounts by file type. 
  • National Death Index (NDI) segment includes the National Death Index cause of death information. This is available for all Medicare beneficiaries from 1999-2008 and for Medicaid recipients from 1999-2007. 

2. Medical Claim Files include fee-for-service (FFS) claims made through Medicare/Medicaid, separated by institutional claim and non-institutional claim.

a) Home Health Agency
b) Hospice
c) Inpatient
d) Skill Nursing Facility
e) Outpatient

f) Carrier
g) Durable Medical Equipment

3. Part D Prescription Medication Claim Files include Part D Drug Event (PDE), Part D Formulary, Part D Drug/Prescriber/Pharmacy Characteristic files and more.

  • PDE data contain prescription drug costs and payment data that enable CMS to make payments to the plans and otherwise administer the Part D benefit.  When a beneficiary fills a prescription under Medicare Part D, a     prescription drug plan sponsor must submit a record to CMS. 
  • Part D Formulary File, beginning in 2010, provides researchers with formulary information and it can be linked to the PDE data.
  • Part D Drug Characteristic File is a supplemental set of variables that are appended to the Part D Event data. The drug characteristics file contains four variables from the First DataBank® (FDB) reference file: brand name, generic name, strength, and form of the drug.
  • Part D Prescriber Characteristics File contains information about the practitioner who prescribed the drug. 
  • Part D Pharmacy Characteristics File provides information about the type of pharmacy (e.g., community/retail pharmacy, mail order, institutional pharmacy), the location of the pharmacy (i.e., state), and whether the pharmacy has a relationship with a common parent organization.

4. Assessment Files include Home Health Outcome and Assessment Information Set (OASIS) and Minimum Data Set (MDS) assessment files.

  • OASIS contains data items that were developed for assessing patient health for the purpose of performance improvement in home health care.
  • MDS is part of the U.S. federally mandated process for clinical assessment of all residents in Medicare or Medicaid certified nursing homes. This process provides a comprehensive assessment of each resident's functional capabilities and helps nursing home staff identify health problems.