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Clinical Document Architecture (CDA) Pilot Project

For more than 10 years, the North American Association of Central Cancer Registries (NAACCR) has provided detailed information for exchanging data from one entity within the cancer registry community to another. NAACCR defined the current method for transmitting a cancer abstract or a cancer public health report from one institution to another in Volume II, Data Standards and Data Dictionary. This fixed-width, column-delimited structure has worked well over the years.

However, given the limitations of the column-delimited format (such as adding new data items, transmitting text fields that are longer than the allowable values, and changing the character length of an existing data item) and NAACCR’s priority to use national health information technology (IT) standards, NAACCR initiated a project to explore alternative message formats that will be consistent with those national health IT formats. After core criteria were applied to a variety of potential formats, the decision was made that the most appropriate format was HL7 Clinical Document Architecture (CDA). To explore the appropriateness of CDA for transmission of the cancer abstract more fully, NAACCR conducted a pilot test transmission of the cancer abstract from a hospital cancer registry to a central cancer registry using the CDA format.

Working in collaboration with NAACCR, CDC’s NPCR provided funding for technical assistance in the form of materials, tools, and guidance for this pilot test. The work scope for this project included—

  1. Developing and documenting an approach for CDA implementation for NAACCR to assess the appropriate implementation steps, if warranted.
  2. Developing an approach to vocabulary mapping that will cover the current NAACCR vocabulary and ultimately provide a clean and reliable method of deploying industry-standard terminologies such as LOINC, NCI Thesaurus, CDC’s PHIN VADS, and SNOMED CT for NAACCR to assess the appropriateness of migrating from local codes to national standards.
  3. Developing a preliminary Implementation Guide (IG) to support implementation by the pilot participants and construct export and import formats for software products.
  4. Developing bi-directional transformation utilities for CDA and NAACCR flat file instances to support EDITS validation and registry insertion, for use in the pilot transmission to assess the capability of allowing multiple formats to co-exist for several years until the CDA format is widespread.
  5. Completing an IG for CDA-based registry submissions for use by NAACCR as a transmission standard, if the pilot test is successful.

Project Implementation Specifications

This project plan anticipated a period of initial implementation before the EDITS software validation for native CDA is available. It included developing utilities to do limited validation checking on CDA at the point of origin. The validation does not support the full suite of rules embodied in EDITS, but should be sufficient to ensure that the CDA instance will convert successfully to flat file format for submission, and will check for basic CDA and NAACCR conformance.

Because of the anticipated length of time for the cancer registry community’s software systems to transition from the flat file format to a CDA format, this project also developed the bi-directional transformation tools to down-translate CDA to the NAACCR fixed-width, column-delimited or flat file format, and to up-translate the NAACCR flat file format to CDA. Flat files will be 100% compatible with CDA, while CDA will be constrained, initially, for conformance with flat file submission. Thus, installations can continue to use the NAACCR flat file format submission without losing semantics while those that convert to CDA can begin to take advantage of the richer format.

Project Vocabulary

The initial CDA IG used the NAACCR code sets and vocabularies as used in NAACCR flat file reporting today. In the future, an advantage of CDA will be adopting controlled terminology compatible with general clinical reporting applications and decision support such as SNOMED CT. Adopting general industry terminology could promote harmonization of the NAACCR data item codes with those used by national standard setters in the electronic health records.

The design of the initial CDA IG, while not specifying the common terminologies, will anticipate a future IG that is compatible with—

  • HL7 Reference Information Model (RIM) design principles and patterns, including the Draft V3 Clinical Statement and HL7 TermInfo projects.
  • HL7 RIM-based structured documents, including the Structured Product Labeling (SPL).
  • Existing and draft CDA clinical document implementation guides including the Care Record Summary (CRS) and Continuity of Care Document (CCD).

Compatibility with these design patterns and vocabularies may support reuse and integration of cancer registry data for clinical trials, patient safety through drug-drug interaction checking against the medical record, and quality enhancement of registry data for public health purposes.

Project Status

  • The pilot project is complete.
  • A CDA Implementation Guide was developed and test messages were transmitted from pilot participants, specifically from hospital cancer registries to central registries.
  • A report of the project with recommendations has been published.