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= Lexicon =

The Lexicon is a standardized reference for clinical terminology across VHA that enables clinical information to be recorded, transmitted, retrieved, and analyzed in a precise and consistent manner independent of clinic or medical center.

The Lexicon provides a comprehensive Application Program Interface (API) that enables any application that needs to use standardized terminology to be able to interface. At its inception in the early 1990s, the scope of the Lexicon was limited to expressing diagnostic clinical problems in easy-to-understand terminology and associating terms to coding systems such as International Classification of Diseases (ICD), Clinical Modification (ICD-9-CM), Diagnostic and Statistical Manual of Mental Disorders (DSM), and the North American Nursing Diagnosis Association (NANDA).

Over the years, this scope broadened to provide a general purpose utility that serves the terminology needs of many packages, including Problem List (standardized using SNOMED CT), Encounter Forms, Text Integration Utility (TIU), Event Capture, Federal Health Information Exchange (FHIE), and the Laboratory Data Sharing Interoperability (LDSI) project. A number of other VistA applications that need the versioned terminology that Lexicon can provide may be added to this list in the near future.

In addition to providing terminology, the Lexicon provides a coding system update deployment mechanism. This update deployment mechanism is now used to update coding systems that are represented in the Lexicon, in addition to updating standard VistA reference files for the same coding systems that fall outside the Lexicon namespace. Additionally, the same mechanism is used to update coding systems that do not form part of the Lexicon. A large number of applications, packages, and services (VistA and external) are now dependent on the quarterly updates provided by this deployment mechanism. The dependent packages include Integrated Billing, Fee Basis, Automated Information Collection System (AICS), Laboratory, Dental, Prosthetics, Mental Health, Radiology, Surgery, Registration, Patient Care Encounter (PCE), Event Capture, Quality: Audiology and Speech Analysis and Reporting (QUASAR), Home Based Primary Care, Clinical Reminders, Text Integration Utility (TIU), Laboratory Data Sharing Interoperability (LDSI), and standardized Problem List.

All of the functionality and services provided by the Lexicon are expected to be replaced by a broader and deeper range of services through VA Enterprise Terminology Services (VETS) applications in the near future.

= Features =

* Provides a basis for a common language of terminology, so that all members of a health care team can communicate with each other.

* Provides a concept-based terminology that is well defined, understandable, and encodable by multiple coding schemes.

* Provides for site modification of term definitions. These modifications are captured by the software and transmitted to the Lexicon team for ratification and possible inclusion in future updates.

* Provides the ability to deploy updates to code systems from Standards Development Organizations (SDOs) that are required by statute, mandated by an oversight body, or required by VHA business needs. The current systems include CPT, HCPCS, CPT modifiers, ICD-9 Diagnoses, ICD-9 Procedures, and SNOMED CT.

* Provides for user definable (user, specialty, or clinic) controlled views of vocabulary through the use of subsets that may be based on a combination of semantic types and code sources.

* Accepts the provider term if a search of the dictionary does not find a match.

* These terms (otherwise known as unresolved narratives) are captured by the software and forwarded to the Lexicon team for analysis and possible inclusion in future updates.

* Allows abbreviations or shortcuts to provide quick access to frequently used definitions.

* Supports CPT, HCPCS, ICD-9-CM Diagnoses, DoD DMIS-IDs, and SNOMED CT coding systems.

* Optimizes search results by placing the most frequently-used terms near the start of the list.

* Supports coding system versioning, activation history, and code text history.

* Supports assignment of a VA Unique Identifier (VU ID) to a concept.

* Supports code stratification and merging.

* Supports synonyms, lexical variants, plural forms, abbreviations, word order variants, keywords, and excluded words.

* Supports inter-coding system mappings.