User:Little pob/Medical classification

Medical classifications, and medical nomenclatures, are used to translate clinical statements into numeric or alphanumeric codes as part of the clinical coding process. They can also be used to translate the codes back into medical terminology. Though, by their nature, a nomenclature is more likely to reflect the original phrasing than a classification.

A medical nomenclature will contain code sets for one or more of the following: diagnosis codes, procedure codes, pharmaceutical codes, or topographical codes; a medical classification is more likely to cover only one of these areas. The data generated are primarily used for statistical analysis; generating case mixes, for example. The data also have several secondary functions, such as medical billing.

Globally, there are country specific and internationally recognised classification systems in use.

Classification types
Many different medical code sets exist, and they can be split into into two main groupings: and.

Statistical classification
A statistical classification brings together similar clinical concepts by grouping them into categories. The number of categories is limited so that the classification does not become too big. Because of this limitation, "residual" categories have to be provided also. These allow the coder to still capture conditions, procedures and so forth that do not have a more specific code, or inclusion term, within the classification.

The International Statistical Classification of Diseases and Related Health Problems, also known as the ICD, is the most widely recognized diagnostic classification. Currently the ICD groups related diseases, conditions or concepts into categories, which are then sorted into chapters. One such chapter is Chapter IX: Diseases of the circulatory system, which contains the codes I00–I99. One of the codes in this chapter is, which has the code title. However, there are several other clinical concepts that are also included here. Among them are paroxysmal atrial tachycardia, paroxysmal junctional tachycardia, auricular tachycardia and nodal tachycardia.

The ICD is maintained by the World Health Organization (WHO). The primary purpose of the ICD is to categorise diseases for both morbidity and mortality reporting. However, the data produced can also be used for additional purposes, such as reimbursement. The tenth edition of the ICD, ICD-10, was endorsed by WHO in 1990, and WHO Member states first began using the classification system in 1994. The eleventh edition, ICD-11, is currently under development.

Nomenclature
With a medical nomenclature there is a separate listing and code for every clinical concept. This means that each of the different tachycardias listed in the example above would have it's own code. Whilst having every clinical term available allows greater specificity, it makes nomenclatures unwieldy for compiling health statistics. As such, coding software that uses a nomenclature will be 'cross-mapped' to the mandated classification. These cross-maps are derived through a process known as ontology, by experts known as nosologists.

The Systematized Nomenclature of Medicine (SNOMED) is the most widely recognised nomenclature in healthcare. 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. SNOMED CT is often described as a reference terminology. SNOMED CT contains more than 311,000 active concepts with unique meanings and formal logic-based definitions organised into hierarchies. As well as anyone with an Affiliate License; SNOMED CT can be used by 40 low income countries (defined by the World Bank, and qualifying research, humanitarian, or charitable projects. SNOMED-CT is designed to be managed by computer, and it is a complex relationship concepts.

WHO Family of International Classifications
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. This (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.

Reference classifications
International Statistical Classification of Diseases and Related Health Problems (ICD)
 * ICD-10 - 10th revision of the ICD. In use since 1994.
 * International Classification of Functioning, Disability and Health (ICF)
 * International Classification of Health Interventions (ICHI) (previously known as International Classification of Procedures in Medicine)

Derived classifications
There are a number of derived works based on the WHO-FIC reference publications. Some are developed by WHO themselves; others by third party organizations, with or without WHO input. These third parties are often the classifications service of a particular country; for example, Australia's National Centre for Classification in Health was the original developer of the ICD-10-AM.

Daughter classifications
WHO publish several sub-classifications that are build upon one of the reference classifications (i.e. ICD and ICF). Examples include the following:


 * International Classification of Diseases for Oncology, Third Edition (ICD-O-3)
 * ICD-10 for Mental and Behavioural Disorders
 * Application of the International Classification of Diseases to Dentistry and Stomatology, 3rd Edition (ICD-DA)
 * Application of the International Classification of Diseases to Neurology (ICD-NA)

Third party derivations
There are several derived classifications in use worldwide. Some are designed to fulfil a national requirement. Others are designed to be used internationally; or go on to be used by other countries. Examples include:


 * The codes in DSM-5, and it's predecessor DSM-IV, build upon the ICD-9-CM codes that classified mental health conditions. The Diagnostic and Statistical Manual of Mental Disorders (DSM) is developed and maintained by the American Psychiatric Association. However, it's use is international.
 * ICD-10-AM (Australian Modification) is used in both Australia and New Zealand.
 * ICD-10-CA is Canada's national version of ICD-10.
 * ICD-10-CM - ICD-10 Clinical Modification; the diagnostic coding system used in the USA since October 2015.
 * EUROCAT - an extension of the ICD-10 Chapter XVII for coding congenital disorders

Related classifications
Related classifications in the WHO-FIC, are WHO publications that refer to a reference classifications, i.e. only at specific chapters or levels. They include:


 * Anatomical Therapeutic Chemical Classification System with Defined Daily Doses (ATC/DDD)
 * International Classification of External Causes of Injury (ICECI)
 * International Classification for Nursing Practice (ICNP)
 * International Classification of Primary Care (ICPC)
 * ICPC-2 PLUS
 * Technical aids for persons with disabilities: Classification and terminology (ISO9999)

Retired classifications

 * ICD-1 through ICD-8
 * ICD-9 - 9th revision of the ICD. Published in 1977, but no longer in use.

Other medical classifications
There are several other classifications produced by other organizations.

Diagnosis
Diagnosis codes can be used to record both morbidity and mortality, as well as the ICD they include:
 * International Classification of Headache Disorders 2nd Edition (ICHD-II)
 * International Classification of Sleep Disorders (ICSD)
 * Online Mendelian Inheritance in Man, database of genetic codes
 * Read codes

Procedure
The categories in a procedure classification are used to identify specific health interventions undertaken by health professionals. Examples include:
 * Australian Classification of Health Interventions (ACHI)
 * Canadian Classification of Health Interventions (CCI)
 * Current Procedural Terminology (CPT)
 * Health Care Procedure Coding System (HCPCS)
 * ICD-10-PCS
 * OPCS Classification of Surgical Operations and Procedures (OPCS-4)

Pharmaceutical
Pharmaceutical codes are used to identify medications. For example:
 * Anatomical Therapeutic Chemical Classification System (AT)
 * Classification of Pharmaco-Therapeutic Referrals (CPR)
 * National Drug Code (NDC)
 * NHS OPCS-4 Chemotherapy Regimens and High Cost Drugs lists

Topographical
Topographical codes are used to indicate a specific location in the body. Some examples:
 * Nomina Anatomica
 * SNOMED

Veterinary
Veterinary medical codes include
 * VeNom codes
 * U.S. Animal Hospital Codes
 * VetSCT the Veterinary Extension to SNOMED CT

Other

 * Logical Observation Identifiers Names and Codes (LOINC), standard for identifying medical laboratory observations
 * Medical Dictionary for Regulatory Activities (MedDRA), used in clinical trials
 * Medical Subject Headings (MeSH)
 * Nursing Interventions Classification (NIC)
 * Nursing Outcomes Classification (NOC)
 * TIME-ITEM, ontology of topics in medical education
 * TNM Classification of Malignant Tumors
 * Unified Medical Language System (UMLS)

Library classification that have medical components

 * Dewey Decimal System and Universal Decimal Classification (section 610–620)
 * National Library of Medicine classification

SNOMED CT vs ICD
SNOMED CT and ICD are designed for different purposes and each should each be used for the purposes for which it was designed. As a core terminology for the EHR, SNOMED CT provides a common language that enables a consistent language that enables a consistent way of capturing, sharing, and aggregating health data across specialties and sites of care. It is highly detailed terminology designed for input not reporting. Classification systems such as ICD-9-CM, ICD-10-CM, and ICD-10-PCS group together similar diseases and procedures and organise related entities for easy retrieval. They are typically used for external reporting requirements or other uses where data aggregation is advantageous, such as measuring the quality of care monitoring resource utilisation, or processing claims for reimbursement. SNOMED is clinically-based, document whatever is needed for patient care and has better clinical coverage than ICD. ICD’s focus is statistical with less common diseases get lumped together in “catch-all” categories, which result in loss of information. SNOMED CT is used directly by healthcare providers during the process of care, whereas ICD is used by coding professionals after the episode of care. SNOMED CT had multiple hierarchy, whereas single hierarchy for ICD. SNOMED CT concepts are defined logically by their attributes, whereas only textual rules and definitions in ICD.

Data Mapping of SNOMED CT and ICD
SNOMED CT and ICD can be coordinated through cross mapping, which is the process of identifying relationships between two distinct data models. The full value of the health information contained in an electronic health record system will only be realized if both systems involved in the map are up to date and accurately reflect the current practice of medicine.