Amedical classification is used to transform descriptions of medicaldiagnoses orprocedures into standardized statistical code in a process known asclinical coding. Diagnosis classifications listdiagnosis codes, which are used to trackdiseases and other health conditions, inclusive of chronic diseases such asdiabetes mellitus andheart disease, and infectious diseases such asnorovirus, theflu, andathlete's foot. Procedure classifications listprocedure codes, which are used to capture interventional data. These diagnosis and procedure codes are used by health care providers, government health programs, private health insurance companies, workers' compensation carriers, software developers, and others for a variety of applications inmedicine,public health andmedical informatics, including:
There are country specific standards and international classification systems.
Many different medical classifications exist, though they occur in two main groupings:Statistical classifications andNomenclatures.
A statistical classification brings together similar clinical concepts and groups them into categories. The number of categories is limited so that the classification does not become too big. An example of this is used by theInternational Statistical Classification of Diseases and Related Health Problems (known as ICD). ICD-10 groups diseases of the circulatory system into one "chapter", known as ChapterIX, covering codes I00–I99. One of the codes in this chapter (I47.1) has the code title (rubric)Supraventricular tachycardia. However, there are several other clinical concepts that are also classified here. Among them are paroxysmalatrial tachycardia, paroxysmaljunctional tachycardia, auricular tachycardia and nodal tachycardia.
Another feature of statistical classifications is the provision of residual categories for "other" and "unspecified" conditions that do not have a specific category in the particular classification.
In anomenclature there is a separate listing and code for every clinical concept. So, in the previous example, each of the listed tachycardias would have its own code. This makes nomenclatures unwieldy for compiling health statistics.
Types of coding systems specific to health care include:
TheWorld Health Organization (WHO) maintains several internationally endorsed classifications designed to facilitate the comparison of health related data within and across populations and over time as well as the compilation of nationally consistent data.[2] This "Family of International Classifications" (FIC) includes three main (or reference) classifications on basic parameters ofhealth prepared by the organization and approved by theWorld Health Assembly for international use, as well as a number of derived and related classifications providing additional details. Some of these international standards have been revised and adapted by various countries for national use.
Derived classifications are based on the WHO reference classifications (i.e., ICD and ICF).[2] They include the following:
Several countries have developed their own version of WHO-FIC publications, which go beyond a local language translation. Many of these are based on the ICD:
Related classifications in the WHO-FIC are those that partially refer to the reference classifications, e.g., only at specific levels.[2] They include:
ICD versions before ICD-9 are not in use anywhere.[16]ICD-9 was published in 1977, and superseded by ICD-10 in 1994. The last version of ICD-10 was published in 2019, and it was replaced by ICD-11 on 1 January 2022.[17] As of February 2022,[update] 35 of the 194 member states have made the transition to the latest version of the ICD.[18]
TheInternational Classification of Procedures in Medicine (ICPM) is aprocedural classification that has not updated since 1989, and will be replaced byICHI.[19] National adaptions of the ICPM includesOPS-301, which is the official German procedural classification.[20]
International Classification of External Causes of Injury (ICECI) was last updated in 2003 and, with the developmentICD-11, is no longer maintained.[21] The concepts of ICECI are represented within ICD-11 as extension codes.
The categories in a diagnosis classification classifydiseases, disorders, symptoms and medical signs. In addition to theICD and its national variants, they include:
The categories in a procedure classification classify specific health interventions undertaken byhealth professionals. In addition to theICHI andICPC, they include:
Drugs are often grouped into drug classes. Such classifications include:
National Drug File-Reference Terminology was a terminology maintained by theVeterans Health Administration (VHA). It groups drug concepts into classes. It was part of RxNorm until March 2018.
Medication Reference Terminology (MED-RT) is a terminology created and maintained byVeterans Health Administration in theUnited States.[24] In 2018, it replaced NDF-RT that was used during 2005–2017. Med-RT is not included in RxNorm but is included in National Library of Medicine'sUMLS Metathesaurus. Prior 2017, NDF-RT was included in RxNorm. The first release of MED-RT was in the spring of 2018.[25][26][27][28]
The Systematized Nomenclature of Medicine (SNOMED) is the most widely recognised nomenclature in healthcare.[30] Its current version, SNOMED Clinical Terms (SNOMED CT), is intended to provide a set of concepts and relationships that offers a common reference point for comparison and aggregation of data about the health care process.[31] SNOMED CT is often described as a reference terminology.[32] SNOMED CT contains more than 311,000 active concepts with unique meanings and formal logic-based definitions organised into hierarchies.[31] SNOMED CT can be used by anyone with an Affiliate License, 40 low income countries defined by the World Bank or qualifying research, humanitarian and charitable projects.[31] SNOMED CT is designed to be managed by computer, and it is a complex relationship concepts.[30]
The International Classification of Disease (ICD) is the most widely recognized medical classification. Maintained by theWorld Health Organization (WHO),[33] its primary purpose is to categorise diseases for morbidity and mortality reporting. However the coded data is often used for other purposes too; including reimbursement practices such asmedical billing. ICD has a hierarchical structure, and coding in this context, is the term applied when representations are assigned to the words they represent.[33] Coding diagnoses and procedures is the assignment of codes from a code set that follows the rules of the underlying classification or other coding guidelines. The current version of the ICD,ICD-10, was endorsed byWHO in 1990. WHO Member states began using the ICD-10 classification system from 1994 for both morbidity and mortality reporting. The exception was the US, who only began using it for reporting mortality in 1999 whilst continuing to useICD-9-CM for morbidity reporting. The US only adopted its version of ICD-10 in October 2015. The delay meant it was unable to compare US morbidity data with the rest of the world during this period. The next major version of the ICD,ICD-11, was ratified by the 72ndWorld Health Assembly on 25 May 2019, and member countries have been able to report data using ICD-11 codes since 1 January 2022.[17]ICD-11 is a fully digital product with integration of clinical terminology and classification. It allows documentation at any level of detail. It includes extension codes, a terminology system, with medicaments, chemicals, infections agents, histopathology, anatomy and mechanisms, objects and animals, and other elements that serve to describe sources of injury or harm.
SNOMED CT andICD were originally designed for different purposes and each should be used for the purposes for which they were designed.[34] As a core terminology for theEHR, SNOMED CT andICD-11 provide a common language that enables a consistent way of capturing, and sharing health data across specialities and sites of care. SNOMED is a highly detailed terminology designed for input not reporting, without a specific use case.ICD-11 and SNOMED, are clinically based, and document whatever is needed for patient care. In contrast to SNOMED, ICD-11 allows full clinical documentation while permitting internationally agreed statistical aggregation for specificuse cases. The foundation of ICD-11 together with theWHO Classification of Health Interventions (ICHI) and theWHO Classification for Functioning, Disability and Health (ICF), comprising also the WHO lists of anatomy, substances and more, are a complete ecosystem for lossless documentation in digital records and at the same time they address specific usecases for data aggregation in a multilingual, freely usable way. SNOMED CT and ICD are used directly by healthcare providers during the process of care,[35] in addition, ICD can be also used for coding after the episode of care, in lower technology environments. SNOMED CT has multiple hierarchy, whereas there is single primary hierarchy for ICD-11 with alternative multiple hierarchies. SNOMED CT concepts are defined logically by their attributes, as is the case in ICD-11, that in addition has textual rules and definitions.
SNOMED andICD can be coordinated. TheNational Library of Medicine (NLM) maps ICD-9-CM, ICD-10-CM, ICD-10-PCS, and other classification systems to SNOMED.[36] Data Mapping is the process of identifying relationships between two distinct data models.[33]
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Veterinary medical codes include theVeNom Coding Group, the U.S. Animal Hospital Codes, and theVeterinary Extension to SNOMED CT (VetSCT).[citation needed]
Certain countries currently use automated coding
