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. [1] 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.
The ICD is published by the WHO and used worldwide for morbidity and mortality statistics, reimbursement systems, and automated decision support in health care. This system is designed to promote international comparability in the collection, processing, classification, and presentation of these statistics. The ICD is a major project to statistically classify all health disorders, and provide diagnostic assistance. The ICD is a core statistically based classificatory diagnostic system for health care related issues of the WHO Family of International Classifications (WHO-FIC). [2]
The ICD is revised periodically and is currently in its 11th revision. The ICD-11, as it is therefore known, was accepted by WHO's World Health Assembly (WHA) on 25 May 2019 and officially came into effect on 1 January 2022. [3] On 11 February 2022, the WHO stated that 35 countries were using the ICD-11. [4]
The ICD is part of a "family" of international classifications (WHOFIC) that complement each other, also including the International Classification of Functioning, Disability and Health (ICF) which focuses on the domains of functioning (disability) associated with health conditions, from both medical and social perspectives, and the International Classification of Health Interventions (ICHI) that classifies the whole range of medical, nursing, functioning and public health interventions.
The title of the ICD is formally the International Statistical Classification of Diseases and Related Health Problems, although the original title, International Classification of Diseases, is still informally the name by which it is usually known.
In the United States and some other countries, the Diagnostic and Statistical Manual of Mental Disorders (DSM) is preferred for the classification of mental disorders for some purposes.
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In 1860, during the international statistical congress held in London, Florence Nightingale made a proposal that was to result in the development of the first model of systematic collection of hospital data. In 1893, a French physician, Jacques Bertillon, introduced the Bertillon Classification of Causes of Death at a congress of the International Statistical Institute in Chicago. [5] [6]
A number of countries adopted Bertillon's system, which was based on the principle of distinguishing between general diseases and those localized to a particular organ or anatomical site, as used by the City of Paris for classifying deaths. Subsequent revisions represented a synthesis of English, German, and Swiss classifications, expanding from the original 44 titles to 161 titles. In 1898, the American Public Health Association (APHA) recommended that the registrars of Canada, Mexico, and the United States also adopt it. The APHA also recommended revising the system every 10 years to ensure the system remained current with medical practice advances. As a result, the first international conference to revise the International Classification of Causes of Death took place in 1900, with revisions occurring every ten years thereafter. At that time, the classification system was contained in one book, which included an Alphabetic Index as well as a Tabular List. The book was small compared with current coding texts.
The revisions that followed contained minor changes, until the sixth revision of the classification system. With the sixth revision, the classification system expanded to two volumes. The sixth revision included morbidity and mortality conditions, and its title was modified to reflect the changes: International Statistical Classification of Diseases, Injuries and Causes of Death (ICD). Prior to the sixth revision, responsibility for ICD revisions fell to the Mixed Commission, a group composed of representatives from the International Statistical Institute and the Health Organization of the League of Nations. In 1948, the WHO assumed responsibility for preparing and publishing the revisions to the ICD every ten years. [7] WHO sponsored the seventh and eighth revisions in 1957 and 1968, respectively. It later became clear that the established ten year interval between revisions was too short.
The ICD is currently the most widely used statistical classification system for diseases in the world. [8] In addition, some countries—including Australia, Canada, and the United States—have developed their own adaptations of ICD, with more procedure codes for classification of operative or diagnostic procedures.
The ICD-6, published in 1949, was the first to be shaped to become suitable for morbidity reporting. Accordingly, the name changed from International List of Causes of Death to International Statistical Classification of Diseases. The combined code section for injuries and their associated accidents was split into two, a chapter for injuries, and a chapter for their external causes. With use for morbidity there was a need for coding mental conditions, and for the first time a section on mental disorders was added . [9] [10]
The International Conference for the Seventh Revision of the International Classification of Diseases was held in Paris under the auspices of WHO in February 1955. In accordance with a recommendation of the WHO Expert Committee on Health Statistics, this revision was limited to essential changes and amendments of errors and inconsistencies. [10]
The 8th Revision Conference convened by WHO met in Geneva, from 6 to 12 July 1965. This revision was more radical than the Seventh but left unchanged the basic structure of the Classification and the general philosophy of classifying diseases, whenever possible, according to their etiology rather than a particular manifestation. During the years that the Seventh and Eighth Revisions of the ICD were in force, the use of the ICD for indexing hospital medical records increased rapidly and some countries prepared national adaptations which provided the additional detail needed for this application of the ICD.
In the US, a group of consultants was asked to study the ICD-8 for its applicability to various users in the United States. This group recommended that further detail be provided for coding hospital and morbidity data. The American Hospital Association's "Advisory Committee to the Central Office on ICDA" developed the needed adaptation proposals, resulting in the publication of the International Classification of Diseases, Adapted (ICDA). In 1968, the United States Public Health Service published the International Classification of Diseases, Adapted, 8th Revision for use in the United States (ICDA-8). Beginning in 1968, ICDA-8 served as the basis for coding diagnostic data for both official morbidity and mortality statistics in the United States. [10] [11]
The International Conference for the Ninth Revision of the International Statistical Classification of Diseases, Injuries, and Causes of Death, convened by WHO, met in Geneva from 30 September to 6 October 1975. In the discussions leading up to the conference, it had originally been intended that there should be little change other than updating of the classification. This was mainly because of the expense of adapting data processing systems each time the classification was revised.
There had been an enormous growth of interest in the ICD and ways had to be found of responding to this, partly by modifying the classification itself and partly by introducing special coding provisions. A number of representations were made by specialist bodies which had become interested in using the ICD for their own statistics. Some subject areas in the classification were regarded as inappropriately arranged and there was considerable pressure for more detail and for adaptation of the classification to make it more relevant for the evaluation of medical care, by classifying conditions to the chapters concerned with the part of the body affected rather than to those dealing with the underlying generalized disease. [6]
At the other end of the scale, there were representations from countries and areas where a detailed and sophisticated classification was irrelevant, but which nevertheless needed a classification based on the ICD in order to assess their progress in health care and in the control of disease. A field test with a bi-axial classification approach—one axis (criterion) for anatomy, with another for etiology—showed the impracticability of such approach for routine use.[ citation needed ]
The final proposals presented to and accepted by the Conference in 1978 [12] retained the basic structure of the ICD, although with much additional detail at the level of the four digit subcategories, and some optional five digit subdivisions. For the benefit of users not requiring such detail, care was taken to ensure that the categories at the three digit level were appropriate.
As the World Health Organization explains: "For the benefit of users wishing to produce statistics and indexes oriented towards medical care, the 9th Revision included an optional alternative method of classifying diagnostic statements, including information about both an underlying general disease and a manifestation in a particular organ or site. This system became known as the 'dagger and asterisk system' and is retained in the Tenth Revision. A number of other technical innovations were included in the Ninth Revision, aimed at increasing its flexibility for use in a variety of situations." [13]
It was eventually replaced by ICD-10, the version currently in use by the WHO and most countries. Given the widespread expansion in the tenth revision, it is not possible to convert ICD-9 data sets directly into ICD-10 data sets, although some tools are available to help guide users. [14] Publication of ICD-9 without IP restrictions in a world with evolving electronic data systems led to a range of products based on ICD-9, such as MeDRA or the Read directory. [10] [11]
When ICD-9 was published by the World Health Organization (WHO), the International Classification of Procedures in Medicine (ICPM) was also developed (1975) and published (1978). The ICPM surgical procedures fascicle was originally created by the United States, based on its adaptations of ICD (called ICDA), which had contained a procedure classification since 1962. ICPM is published separately from the ICD disease classification as a series of supplementary documents called fascicles (bundles or groups of items). Each fascicle contains a classification of modes of laboratory, radiology, surgery, therapy, and other diagnostic procedures. Many countries have adapted and translated the ICPM in parts or as a whole and are using it with amendments since then. [10] [11]
The International Classification of Diseases, Clinical Modification (ICD-9-CM) was an adaptation created by the US National Center for Health Statistics (NCHS) and used in assigning diagnostic and procedure codes associated with inpatient, outpatient, and physician office utilization in the United States. The ICD-9-CM is based on the ICD-9 but provides for additional morbidity detail. It was updated annually on October 1. [15] [16]
It consists three volumes:
The NCHS and the Centers for Medicare and Medicaid Services are the US governmental agencies responsible for overseeing all changes and modifications to the ICD-9-CM.
Work on ICD-10 began in 1983, and the new revision was endorsed by the Forty-third World Health Assembly in May 1990. The latest version came into effect in WHO Member States starting on 1 January 1993. [18] The classification system allows more than 55,000 different codes and permits tracking of many new diagnoses and procedures, a significant expansion on the 17,000 codes available in ICD-9. [19] Adoption was relatively swift in most of the world. Several materials are made available online by WHO to facilitate its use, including a manual, training guidelines, a browser, and files for download. [2] Some countries have adapted the international standard, such as the "ICD-10-AM" published in Australia in 1998 (also used in New Zealand), [20] and the "ICD-10-CA" introduced in Canada in 2000. [21]
Adoption of ICD-10-CM was slow in the United States. Since 1979, the US had required ICD-9-CM codes [11] for Medicare and Medicaid claims, and most of the rest of the American medical industry followed suit. On 1 January 1999 the ICD-10 (without clinical extensions) was adopted for reporting mortality, but ICD-9-CM was still used for morbidity. Meanwhile, NCHS received permission from the WHO to create a clinical modification of the ICD-10, and has production of all these systems:
On 21 August 2008, the US Department of Health and Human Services (HHS) proposed new code sets to be used for reporting diagnoses and procedures on health care transactions. Under the proposal, the ICD-9-CM code sets would be replaced with the ICD-10-CM code sets, effective 1 October 2013. On 17 April 2012 the Department of Health and Human Services (HHS) published a proposed rule that would delay, from 1 October 2013 to 1 October 2014, the compliance date for the ICD-10-CM and PCS. [22] Once again, Congress delayed implementation date to 1 October 2015, after it was inserted into "Doc Fix" Bill without debate over objections of many.
Revisions to ICD-10-CM Include:
ICD-10-CA is a clinical modification of ICD-10 developed by the Canadian Institute for Health Information for morbidity classification in Canada. ICD-10-CA applies beyond acute hospital care, and includes conditions and situations that are not diseases but represent risk factors to health, such as occupational and environmental factors, lifestyle and psycho-social circumstances. [21]
The eleventh revision of the International Classification of Diseases, or the ICD-11, is almost five times as big as the ICD-10. [23] It was created following a decade of development involving over 300 specialists from 55 countries. [24] [25] [26] 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, [27] and officially endorsed by all WHO members during the 72nd World Health Assembly on 25 May 2019. [28]
For the ICD-11, the WHO decided to differentiate between the core of the system and its derived specialty versions, such as the ICD-O for oncology. As such, the collection of all ICD entities is called the Foundation Component. From this common core, subsets can be derived. The primary derivative of the Foundation is called the ICD-11 MMS, and it is this system that is commonly referred to and recognized as "the ICD-11". [29] MMS stands for Mortality and Morbidity Statistics.
ICD-11 comes with an implementation package that includes transition tables from and to ICD-10, a translation tool, a coding tool, web-services, a manual, training material, and more. [30] All tools are accessible after self-registration from the Maintenance Platform.
The ICD-11 officially came into effect on 1 January 2022, although the WHO admitted that "not many countries are likely to adapt that quickly". [31] In the United States, the advisory body of the Secretary of Health and Human Services has given an expected release year of 2025, but if a clinical modification is determined to be needed (similar to the ICD-10-CM), this could become 2027. [32]
In the United States, the US Public Health Service published The International Classification of Diseases, Adapted for Indexing of Hospital Records and Operation Classification (ICDA), completed in 1962 and expanding the ICD-7 in a number of areas to more completely meet the indexing needs of hospitals. The US Public Health Service later published the Eighth Revision, International Classification of Diseases, Adapted for Use in the United States, commonly referred to as ICDA-8, for official national morbidity and mortality statistics. This was followed by the ICD, 9th Revision, Clinical Modification, known as ICD-9-CM, published by the US Department of Health and Human Services and used by hospitals and other healthcare facilities to better describe the clinical picture of the patient. The diagnosis component of ICD-9-CM is completely consistent with ICD-9 codes, and remains the data standard for reporting morbidity. National adaptations of the ICD-10 progressed to incorporate both clinical code (ICD-10-CM) and procedure code (ICD-10-PCS) with the revisions completed in 2003. In 2009, the US Centers for Medicare and Medicaid Services announced that it would begin using ICD-10 on April 1, 2010, with full compliance by all involved parties by 2013. [19] However, the US extended the deadline twice and did not formally require transitioning to ICD-10-CM (for most clinical encounters) until October 1, 2015.
The years for which causes of death in the United States have been classified by each revision as follows:
Cause of death on United States death certificates, statistically compiled by the Centers for Disease Control and Prevention (CDC), are coded in the ICD, which does not include codes for human and system factors commonly called medical errors. [33] [34]
The various ICD editions include sections that classify mental and behavioural disorders. The ICD-10 Classification of Mental and Behavioural Disorders: Clinical Descriptions and Diagnostic Guidelines – also known as the "blue book" – is derived from Chapter V of ICD-10 and gives the diagnostic criteria for the conditions listed at each category therein. The blue book was developed separately to, but coexists with, the Diagnostic and Statistical Manual of Mental Disorders (DSM) of the American Psychiatric Association—though both seek to use the same diagnostic classifications. A survey of psychiatrists in 66 countries comparing use of the ICD-10 and DSM-IV found that the former was more often used for clinical diagnosis while the latter was more valued for research. [35]
As part of the development of the ICD-11, WHO established an "International Advisory Group" to guide what would become the chapter on "Mental, behavioural or neurodevelopmental disorders". [36] [37] The working group proposed that ICD-11 should declassify the categories within ICD-10 at "F66 Psychological and behavioural disorders that are associated with sexual development and orientation". [36] [38] The group reported to WHO that there was "no evidence" these classifications were clinically useful, as they do not "contribute to health service delivery or treatment selection nor provide essential information for public health surveillance." [36] Adding that; despite ICD-10 explicitly stating "sexual orientation by itself is not to be considered a disorder", the inclusion of such categories "suggest that mental disorders exist that are uniquely linked to sexual orientation and gender expression." A position already recognised by the DSM, as well as other classification systems.
The ICD is actually the official system for the US, [39] although many mental health professionals do not realize this due to the dominance of the DSM.
A psychologist has stated: "Serious problems with the clinical utility of both the ICD and the DSM are widely acknowledged." [40]
The Diagnostic and Statistical Manual of Mental Disorders is a publication by the American Psychiatric Association (APA) for the classification of mental disorders using a common language and standard criteria. It is an internationally accepted manual on the diagnosis and treatment of mental disorders, though it may be used in conjunction with other documents. Other commonly used principal guides of psychiatry include the International Classification of Diseases (ICD), Chinese Classification of Mental Disorders (CCMD), and the Psychodynamic Diagnostic Manual. However, not all providers rely on the DSM-5 as a guide, since the ICD's mental disorder diagnoses are used around the world, and scientific studies often measure changes in symptom scale scores rather than changes in DSM-5 criteria to determine the real-world effects of mental health interventions.
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 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:
Sexual addiction is a state characterized by compulsive participation or engagement in sexual activity, particularly sexual intercourse, despite negative consequences. The concept is contentious; as of 2023, sexual addiction is not a clinical diagnosis in either the DSM or ICD medical classifications of diseases and medical disorders, which instead categorize such behaviors under labels such as compulsive sexual behavior.
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 Psychodynamic Diagnostic Manual (PDM) is a diagnostic handbook similar to the International Statistical Classification of Diseases and Related Health Problems (ICD) or the Diagnostic and Statistical Manual of Mental Disorders (DSM). The PDM was published on May 28, 2006.
The International Classification of Sleep Disorders (ICSD) is "a primary diagnostic, epidemiological and coding resource for clinicians and researchers in the field of sleep and sleep medicine". The ICSD was produced by the American Academy of Sleep Medicine (AASM) in association with the European Sleep Research Society, the Japanese Society of Sleep Research, and the Latin American Sleep Society. The classification was developed as a revision and update of the Diagnostic Classification of Sleep and Arousal Disorders (DCSAD) that was produced by both the Association of Sleep Disorders Centers (ASDC) and the Association for the Psychophysiological Study of Sleep and was published in the journal Sleep in 1979. A second edition, called ICSD-2, was published by the AASM in 2005. The third edition, ICSD-3, was released by the AASM in 2014. A text revision of the third edition (ICSD-3-TR) was published in 2023 by the AASM.
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.
The classification of transgender people (transgender women specifically) into distinct groups has been attempted since the mid-1960s. The most common modern classifications in use are the DSM-5 and ICD, which are mainly used for insurance and administration of gender-affirming care.
The classification of mental disorders, also known as psychiatric nosology or psychiatric taxonomy, is central to the practice of psychiatry and other mental health professions.
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 Classification of Diseases (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 came into effect in member states on 1 January 1993. It was replaced by ICD-11 on January 1, 2022.
Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) has a long history with an evolution in medical understanding, diagnoses and social perceptions.
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.
Simple-type schizophrenia is a sub-type of schizophrenia included in the International Classification of Diseases (ICD-10), in which it is classified as a mental and behaviour disorder. It is not included in the current Diagnostic and Statistical Manual of Mental Disorders (DSM-5) or the upcoming ICD-11, effective 1 January 2022. Simple-type schizophrenia is characterized by negative ("deficit") symptoms, such as avolition, apathy, anhedonia, reduced affect display, lack of initiative, lack of motivation, low activity; with absence of hallucinations or delusions of any kind.
According to some classification systems, Sexual masochism disorder is the condition of experiencing recurring and intense sexual arousal in response to enduring moderate to extreme pain, suffering, or humiliation. The Diagnostic and Statistical Manual (DSM-5) of the American Psychiatric Association indicates that a person may have a masochistic sexual interest but that the diagnosis of sexual masochism disorder would only apply to individuals who also report psychosocial difficulties because of it.
Classification of sleep disorders comprises systems for classifying medical disorders associated with sleep. Systems have changed, increasingly using technological discoveries to advance the understanding of sleep and recognition of sleep disorders.
Organic personality disorder (OPD) or secondary personality change, is a condition described in the ICD-10 and ICD-11 respectively. It is characterized by a significant personality change featuring abnormal behavior due to an underlying traumatic brain injury or another pathophysiological medical condition affecting the brain. Abnormal behavior can include but is not limited to apathy, paranoia and disinhibition.
Other specified dissociative disorder (OSDD) is a mental health diagnosis for pathological dissociation that matches the DSM-5 criteria for a dissociative disorder, but does not fit the full criteria for any of the specifically identified subtypes, which include dissociative identity disorder, dissociative amnesia, and depersonalization/derealization disorder, and the reasons why the previous diagnoses were not met are specified. "Unspecified dissociative disorder" is given when the clinician does not give a reason. The International Statistical Classification of Diseases and Related Health Problems (ICD-10) refers to the diagnosis as "Other dissociative and conversion disorders". Under the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM), it was known as "Dissociative disorder not otherwise specified" (DDNOS).
The ICD-10 Clinical Modification (ICD-10-CM) is a set of diagnosis codes used in the United States of America. It was developed by a component of the U.S. Department of Health and Human services, as an adaption of the ICD-10 with authorization from the World Health Organization. In 2015, ICD-10-CM replaced ICD-9-CM as the federally mandated classification. Annual updates are provided.
The primary linearization, and the one most users will recognize and likely believe is "the ICD-11", is the Mortality and Morbidity Statistics (MMS) linearization.
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: CS1 maint: DOI inactive as of December 2024 (link)Note: Since adoption of ICD-10 CM in the US, several online tools have been mushrooming. They all refer to that particular modification and thus are not linked here.