Data Dictionaries

The Medicare data are contained in a series of data files.

  • The Beneficiary Annual Summary File contains demographic information, including county of residence, dates of death, and comorbidity flags that can be used to identify patients with certain chronic conditions.
  • The Medicare Claims Files contain fully adjudicated paid claims and dates of service for all non-capitated ambulatory, emergency department, inpatient, and outpatient encounters (including administrative claims for laboratory tests), skilled nursing facility, hospice, home health, and durable medical equipment claims for patients at the time of service. Diagnoses and procedures are identified by the International Statistical Classification of Diseases and Related Health Problems (ICD-9); Current Procedural Terminology (CPT); and Health Care Financing Administration (HCFA) Common Procedure Coding System (HCPCS) codes for both outpatient and inpatient visits/stays. Physician, specialist, and emergency room visits, as well as hospital stays, are captured in the database through CPT codes, revenue codes (e.g., room and board), used on billing forms such as the UB-92, and place of service codes. The Medicare Claims files include the following: Carrier RIF, Durable Medical Equipment RIF, Home Health Agency RIF, Hospice RIF, Inpatient RIF, Outpatient RIF, Skilled Nursing Facility RIF, and MedPAR RIF.
  • Prescription Drug Claims (Part D data) include information on dates of dispensing, National Drug Codes (NDCs), strength, amount, and days supply. Other information on prescription drug use is also available. The Part D data are included in the following files: Part D Formulary File, Part D Drug Event File, Part D Drug Characteristics File, Part D Pharmacy Characteristics File, Part D Plan Characteristics File, and Part D Prescriber Characteristics File.

The content of all of these files are described in detail on the ResDAC website. ResDAC, the Research Data Assistance Center, is a contractor for the Center for Medicare and Medicaid Services (CMS) that provides free assistance to academic, government and non-profit researchers interested in using Medicare and/or Medicaid data for their research.