The United States Health Information Knowledgebase (USHIK) is a project funded by the Agency for Healthcare Research and Quality (AHRQ) under the direction of the Department of Health and Human Services (HHS). The project consists of the creation and maintenance of a system of metadata registries and their metadata standards.

A metadata registry is a neutral or impartial repository of metadata from an authoritative source. Metadata registries such as USHIK are used to promote interoperability and reuse of data. The registry does not attempt to change the metadata content but rather provide a structured means of viewing data for the technical as well as the casual user. The registry contains core components as well as specific collections of metadata artifacts. These core components and metadata attributes are based on the ISO/IEC 11179 Standard for Metadata Registries (Part 3 - Registry metamodel and basic attributes).

The USHIK project supports the following goals:

• To provide a tool to compare and evaluate metadata across multiple metadata standards
• To provide a one-stop shop display experience for metadata standards to researchers, clinicians, policy makers, developers, and healthcare metadata users in general
• To support the HHS Secretary`s initiative to promote quality of care by enhancing the quality of data used to provide that care. (It's important that we don't lose sight of our ultimate objective: Improved quality of healthcare for the patient.)
• To promote harmonization across standards
• To support various initiatives from HHS

The initiatives supported include:

• CMS Quality Reporting Programs
• Children's EHR Format
• Common Formats - Center for Quality Improvement and Patient Safety (CQuIPS)
• Health Information Technology Standards Panel (HITSP)
• All-Payer Claims Databases (APCD)
• Standards and Interoperability Framework (S&I)

The core components are:

• Data Elements: The smallest unit of data pertinent to an electronic exchange of information as defined by a particular standard, collection, or initiative.
  Example of Data Element: Race or Ethnicity Code as defined by X12
• Value Domains: A relevant subset of values from a vocabulary
  Example of a Value Domain: Black, Hispanic, Caucasian, Asian or Pacific Islander, Black (Non-Hispanic), White (Non-Hispanic)
• Conceptual Domains: A collection of value meanings Example of a Value Meaning from a Conceptual Domain: Black (Non-Hispanic) - A person having origins in any of the black racial groups of Africa who is not of Mexican, Puerto Rican, Cuban, or South or Central American origin or of any other Spanish culture or origin regardless of race
• Data Element Concepts: A Data Element described independently of any particular representation.
  Example of a Data Element Concept: Ethnicity - An ethnic group is a group of people whose members identify with each other, through a common heritage that is real or assumed. This shared heritage may be based upon putative common ancestry, history, kinship, religion, language, shared territory, nationality or physical appearance.

The metadata collected in USHIK comes from:

• Standards Developing Organizations (SDO)
• Federal and State Organizations
• Specific Harmonization Initiatives
• Other organizations.

The participating Standards Developing Organizations (SDOs) include:

• National Council of Prescription Data Programs (NCPDP)
• Accredited Standards Committee (ASC) X12