A medical classification is used to transform descriptions of medical diagnoses or procedures into standardized statistical code in a process known as clinical coding. Diagnosis classifications list diagnosis codes, which are used to track diseases and other health conditions, inclusive of chronic diseases such as diabetes mellitus and heart disease, and infectious diseases such as norovirus, the flu, and athlete's foot. Procedure classifications list procedure code, 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 in medicine, public health and medical informatics, including:
There are country specific standards and international classification systems.
Many different medical classifications exist, though they occur into two main groupings: Statistical classifications and Nomenclatures.
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 the International Statistical Classification of Diseases and Related Health Problems (known as ICD). ICD-10 groups diseases of the circulatory system into one "chapter", known as Chapter IX, 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 paroxysmal atrial tachycardia, paroxysmal junctional 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 a nomenclature there is a separate listing and code for every clinical concept. So, in the previous example, each of the tachycardia listed would have its own code. This makes nomenclatures unwieldy for compiling health statistics.
Types of coding systems specific to health care include:
The World 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) include three main (or reference) classifications on basic parameters of health prepared by the organization and approved by the World 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]
The International Classification of Procedures in Medicine (ICPM) is a procedural classification that has not updated since 1989, and will be replaced by ICHI. [19] National adaptions of the ICPM includes OPS-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 development ICD-11, is no longer maintained. [21] The concepts of ICECI are represented within ICD-11 as extension codes.
The categories in a diagnosis classification classify diseases, disorders, symptoms and medical signs. In addition to the ICD and its national variants, they include:
The categories in a procedure classification classify specific health interventions undertaken by health professionals. In addition to the ICHI and ICPC, they include:
Drugs are often grouped into drug classes. Such classifications include:
National Drug File-Reference Terminology was a terminology maintained by the Veterans 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 by Veterans Health Administration in the United 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's UMLS Metathesaurus. Prior 2017, NDF-RT was included in RxNorm. The first release of MED-RT was in the spring of 2018. [25]
The United States Food and Drug Administration requires in its Manual of Policies and Procedures (MaPP) 7400.13 dated July 18, 2013 and updated on July 25, 2018, that MED-RT be used for selecting an established pharmacologic class (EPC) for the Highlights of Prescribing Information in drug labeling. Each EPC text phrase is associated with a term known as an EPC concept. EPC concepts use a standardized format derived from the U.S. Department of Veterans Affairs, Veterans Health Administration (VHA) Medication Reference Terminology (MED-RT). Each EPC concept also has a unique standardized alphanumeric identifier code, used as the machine-readable tag for the concept. These codes enable SPL indexing. The exact EPC text phrase used in INDICATIONS AND USAGE in Highlights might not be identical to the wording used to describe the EPC concept, because the standardized language used for the EPC concept might not be considered sufficiently clear to the readers of the labeling. Each active moiety also may be assigned MOA, PE, and CS standardized indexing concepts, which are also linked to unique standardized alphanumeric identifier codes. MOA, PE, and CS standardized indexing concepts may or may not be related to the therapeutic effect of the active moiety for a particular indication, but they should still be scientifically valid and clinically meaningful. Even if the MOA, PE, and CS standardized indexing concepts are not known with certainty to be related to the therapeutic effect, they may still be useful for identifying drug interactions and permitting other safety assessments for a moiety based upon appropriate and relevant considerations, such as enzyme inhibition and enzyme induction. MOA, PE, and CS concepts are maintained in a standardized format as part of the MED-RT hierarchy. https://www.fda.gov/media/86437/download
The United States Food and Drug Administration Study Data Technical Conformance Guide dated July 2020 states, "6.5 Pharmacologic Class 6.5.1 Medication Reference Terminology 6.5.1.1 General Considerations The Veterans Administration's Medication Reference Terminology (MED-RT) should be used to identify the pharmacologic class(es) of all active investigational substances that are used in a study (either clinical or nonclinical). This information should be provided in the SDTM TS domain when a full TS is indicated. The information should be provided as one or more records in TS, where TSPARMCD= PCLAS. Pharmacologic class is a complex concept that is made up of one or more component concepts: mechanism of action (MOA), physiologic effect (PE), and chemical structure (CS).51 The established pharmacologic class is generally the MOA, PE, or CS term that is considered the most scientifically valid and clinically meaningful. Sponsors should include in TS (the full TS) the established pharmacologic class of all active moieties of investigational products used in a study. FDA maintains a list of established pharmacologic classes of approved moieties.52 If the established pharmacologic class is not available for an active moiety, then the sponsor should discuss the appropriate MOA, PE, and CS terms with the review division. For unapproved investigational active moieties where the pharmacologic class is unknown, the PCLAS record may not be available." https://www.fda.gov/media/136460/download
The United States Food and Drug Administration publishes a Data Standards Catalog that lists the data standards and terminologies that FDA supports for use in regulatory submissions to better enable the evaluation of safety, effectiveness, and quality of FDA-regulated products. In addition, the FDA has the statutory and regulatory authority to require certain standards and terminologies and these are identified in the Catalog with the date the requirement begins and, as needed, the date the requirement ends, and information sources. The submission of data using standards or terminologies not listed in the Catalog should be discussed with the Agency in advance. Where the Catalog expresses support for more than one standard or terminology for a specific use, the sponsor or applicant may select one to use or can discuss, as appropriate, with their review division. Version 7.0 of the FDA Data Standards Catalog dated 03-15-2021, specifies that MED-RT was a required terminology by the White House Consolidated Health Informatics Initiative in various Federal Register Notices beginning as early as May 6, 2004, for NDAs, ANDAs, and certain BLAs beginning on December 17, 2016, and for certain IND's beginning on December 17, 2017. https://www.fda.gov/media/85137/download
The Systematized Nomenclature of Medicine (SNOMED) is the most widely recognised nomenclature in healthcare. [27] 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. [28] SNOMED CT is often described as a reference terminology. [29] SNOMED CT contains more than 311,000 active concepts with unique meanings and formal logic-based definitions organised into hierarchies. [28] 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. [28] SNOMED CT is designed to be managed by computer, and it is a complex relationship concepts. [27]
The International Classification of Disease (ICD) is the most widely recognized medical classification. Maintained by the World Health Organization (WHO), [30] 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 as medical billing. ICD has a hierarchical structure, and coding in this context, is the term applied when representations are assigned to the words they represent. [30] 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 by WHO 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 use ICD-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 72nd World 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 and ICD were originally designed for different purposes and each should be used for the purposes for which they were designed. [31] As a core terminology for the EHR, SNOMED CT and ICD-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 specific use cases. The foundation of ICD-11 together with the WHO Classification of Health Interventions (ICHI) and the WHO 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, [32] 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 and ICD can be coordinated. The National Library of Medicine (NLM) maps ICD-9-CM, ICD-10-CM, ICD-10-PCS, and other classification systems to SNOMED. [33] Data Mapping is the process of identifying relationships between two distinct data models. [30]
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Veterinary medical codes include the VeNom Coding Group, the U.S. Animal Hospital Codes, and the Veterinary Extension to SNOMED CT (VetSCT).[ citation needed ]
The International Classification of Diseases (ICD) is a globally used medical classification used in epidemiology, health management and for clinical purposes. The ICD is maintained by the World Health Organization (WHO), which is the directing and coordinating authority for health within the United Nations System. The ICD is originally designed as a health care classification system, providing a system of diagnostic codes for classifying diseases, including nuanced classifications of a wide variety of signs, symptoms, abnormal findings, complaints, social circumstances, and external causes of injury or disease. This system is designed to map health conditions to corresponding generic categories together with specific variations, assigning for these a designated code, up to six characters long. Thus, major categories are designed to include a set of similar diseases.
Nosology is the branch of medical science that deals with the classification of diseases. Fully classifying a medical condition requires knowing its cause, the effects it has on the body, the symptoms that are produced, and other factors. For example, influenza is classified as an infectious disease because it is caused by a virus, and it is classified as a respiratory infection because the virus infects and damages certain tissues in the respiratory tract. The more that is known about the disease, the more ways the disease can be classified nosologically.
A subscription-based product of the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH), MedDRA or Medical Dictionary for Regulatory Activities is a clinically validated international medical terminology dictionary-thesaurus used by regulatory authorities and the biopharmaceutical industry during the regulatory process, from pre-marketing to post-marketing activities, and for safety information data entry, retrieval, evaluation, and presentation. Also, it is the adverse event classification dictionary.
The Systematized Nomenclature of Medicine (SNOMED) is a systematic, computer-processable collection of medical terms, in human and veterinary medicine, to provide codes, terms, synonyms and definitions which cover anatomy, diseases, findings, procedures, microorganisms, substances, etc. It allows a consistent way to index, store, retrieve, and aggregate medical data across specialties and sites of care. Although now international, SNOMED was started in the U.S. by the College of American Pathologists (CAP) in 1973 and revised into the 1990s. In 2002 CAP's SNOMED Reference Terminology was merged with, and expanded by, the National Health Service's Clinical Terms Version 3 to produce SNOMED CT.
Procedure codes are a sub-type of medical classification used to identify specific surgical, medical, or diagnostic interventions. The structure of the codes will depend on the classification; for example some use a numerical system, others alphanumeric.
In health care, diagnosis codes are used as a tool to group and identify diseases, disorders, symptoms, poisonings, adverse effects of drugs and chemicals, injuries and other reasons for patient encounters. Diagnostic coding is the translation of written descriptions of diseases, illnesses and injuries into codes from a particular classification. In medical classification, diagnosis codes are used as part of the clinical coding process alongside intervention codes. Both diagnosis and intervention codes are assigned by a health professional trained in medical classification such as a clinical coder or Health Information Manager.
The International Classification of Health Interventions (ICHI) is a system of classifying procedure codes being developed by the World Health Organization (WHO). It is currently available as a beta 3 release. The components for clinical documentation are stable. The component on public health interventions is in the process of being finalized. Updates on development and status of the classification are listed on WHO home page.
Logical Observation Identifiers Names and Codes (LOINC) is a database and universal standard for identifying medical laboratory observations. First developed in 1994, it was created and is maintained by the Regenstrief Institute, a US nonprofit medical research organization. LOINC was created in response to the demand for an electronic clinical care and management database and is publicly available at no cost.
SNOMED CT or SNOMED Clinical Terms is a systematically organized computer-processable collection of medical terms providing codes, terms, synonyms and definitions used in clinical documentation and reporting. SNOMED CT is considered to be the most comprehensive, multilingual clinical healthcare terminology in the world. The primary purpose of SNOMED CT is to encode the meanings that are used in health information and to support the effective clinical recording of data with the aim of improving patient care. SNOMED CT provides the core general terminology for electronic health records. SNOMED CT comprehensive coverage includes: clinical findings, symptoms, diagnoses, procedures, body structures, organisms and other etiologies, substances, pharmaceuticals, devices and specimens.
The International Classification of Primary Care (ICPC) is a classification method for primary care encounters. The ICPC-3 strives to be a person centered classification for Primary Care, building on the foundations of the ICPC-2. It includes references to existing international standards such as ICD-10, ICD-11, ICF as well as SNOMED CT clinical terminology. It provides a framework for documenting and organizing clinical data from primary care patient contacts.
Medcin, is a system of standardized medical terminology, a proprietary medical vocabulary and was developed by Medicomp Systems, Inc. MEDCIN is a point-of-care terminology, intended for use in Electronic Health Record (EHR) systems, and it includes over 280,000 clinical data elements encompassing symptoms, history, physical examination, tests, diagnoses and therapy. This clinical vocabulary contains over 38 years of research and development as well as the capability to cross map to leading codification systems such as SNOMED CT, CPT, ICD-9-CM/ICD-10-CM, DSM, LOINC, CDT, CVX, and the Clinical Care Classification (CCC) System for nursing and allied health.
A clinical coder—also known as clinical coding officer, diagnostic coder, medical coder, or nosologist—is a health information professional whose main duties are to analyse clinical statements and assign standardized codes using a classification system. The health data produced are an integral part of health information management, and are used by local and national governments, private healthcare organizations and international agencies for various purposes, including medical and health services research, epidemiological studies, health resource allocation, case mix management, public health programming, medical billing, and public education.
ICD-10 is the 10th revision of the International Statistical Classification of Diseases and Related Health Problems (ICD), a medical classification list by the World Health Organization (WHO). It contains codes for diseases, signs and symptoms, abnormal findings, complaints, social circumstances, and external causes of injury or diseases. Work on ICD-10 began in 1983, became endorsed by the Forty-third World Health Assembly in 1990, and was first used by member states in 1994. It was replaced by ICD-11 on January 1, 2022.
The following outline is provided as an overview of and topical guide to clinical research:
OPCS-4, or more formally OPCS Classification of Interventions and Procedures version 4, is the procedural classification used by clinical coders within National Health Service (NHS) hospitals of NHS England, NHS Scotland, NHS Wales and Health and Social Care in Northern Ireland. It is based on the earlier Office of Population Censuses and Surveys Classification of Surgical Operations and Procedures, and retains the OPCS abbreviation from this now defunct publication.
The ICD-11 is the eleventh revision of the International Classification of Diseases (ICD). It replaces the ICD-10 as the global standard for recording health information and causes of death. The ICD is developed and annually updated by the World Health Organization (WHO). Development of the ICD-11 started in 2007 and spanned over a decade of work, involving over 300 specialists from 55 countries divided into 30 work groups, with an additional 10,000 proposals from people all over the world. Following an alpha version in May 2011 and a beta draft in May 2012, a stable version of the ICD-11 was released on 18 June 2018, and officially endorsed by all WHO members during the 72nd World Health Assembly on 25 May 2019.
The Omaha System is a standardized health care terminology consisting of an assessment component, a care plan/services component, and an evaluation component. Approximately 22,000 health care practitioners, educators, and researchers use Omaha System to improve clinical practice, structure documentation, and analyze secondary data. Omaha System users from Canada, China, The Czech Republic, Estonia, Hong Kong, Japan, Mexico, New Zealand, The Netherlands, Turkey, the United States, and Wales, have presented at Omaha System International Conferences.
Read codes are a clinical terminology system that was in widespread use in General Practice in the United Kingdom until around 2018, when NHS England switched to using SNOMED CT. Read codes are still in use in Scotland and in England were permitted for use in NHS secondary care settings, such as dentistry and mental health care until 31 March 2020. Read codes support detailed clinical encoding of multiple patient phenomena including: occupation; social circumstances; ethnicity and religion; clinical signs, symptoms and observations; laboratory tests and results; diagnoses; diagnostic, therapeutic or surgical procedures performed; and a variety of administrative items. It therefore includes but goes significantly beyond the expressivity of a diagnosis coding system.
The Clinical Care Classification (CCC) System is a standardized, coded nursing terminology that identifies the discrete elements of nursing practice. The CCC provides a unique framework and coding structure. Used for documenting the plan of care; following the nursing process in all health care settings.
Intelligent Medical Objects (IMO) is a privately held company specializing in developing, managing and licensing medical vocabularies. IMO partners with various health care organizations, medical content providers and EHR developers.
Certain countries currently use automated coding
