The Centers for Medicare & Medicaid Services (CMS) launched the Chronic Conditions Warehouse (CCW), a research database, in response to the Medicare Modernization Act of 2003 (MMA). Section 723 of the MMA outlined a plan to improve the quality of care and reduce the cost of care for chronically ill Medicare beneficiaries. In addition to chronic conditions, the CCW supports health policy analysis and other CMS initiatives.

  • Introduction to CCW:  View this Chronic Conditions Warehouse informational video to learn how you can access, analyze, and aggregate all the data you need like never before!


The Beneficiary Link

The CCW data are linked by a unique, unidentifiable beneficiary key, which allows researchers to analyze information across the continuum of care.

The CCW is designed to:

  • Follow beneficiaries across multiple care settings
  • Identify areas for improving quality of care provided to chronically ill Medicare beneficiaries
  • Identify ways to reduce program spending
  • Make current Medicare, Medicaid, Assessment and Part D data more readily available to researchers for all types of studies, populations, and rare events
  • Provide thorough documentation so researchers understand the common keys, relationships between claims types, and how to use data accurately

Data Availability

CCW contains the following 100% Medicare files for years 1999 - 2021:

  • Fee-for-service institutional and non-institutional claims
  • Enrollment/eligibility
  • Assessment data

100% Medicare Encounter records for years 2015-2021

100% Medicaid files for years 1999 - 2021

100% Part D Prescription Drug Event data for years 2006 - 2022

CCW data files may be requested for any of the predefined chronic condition cohorts, or users may request a customized cohort(s) specific to research focus areas.