29 International classification of diseases and causes of death

Nupur Mahajan and Gautam Kshatriya

epgp books

 

 

 

Contents:

  • International Classification of Disease: Introduction
  • Historical development
  • Basic structure and principles of ICD
  • International Nomenclature of Disease (IND)
  • Differences between ICD and DSM
  • Versions of ICD
  • Uses of ICD
  • Limitations of ICD
  • Future prospects

    Learning Objectives:

  • To understand what is International classification of Diseases.
  • To gain knowledge about its historical development.
  • To know about the underlying principles and structure of classification of ICD.
  • To differentiate between International Classification of Disease and Diagnostic and Statistical Manual.
  • To acquaint ourselves with the versions of ICD, uses and limitations of ICD.
  • To comprehend the future prospects of ICD.

    Introduction

 

The International Classification of Diseases (ICD) is a diagnostic tool which is being in use in the field of medicine all across the globe. Currently the ICD is in its tenth revision and is referred to as ICD-10. This revision handbook classifies medical diseases and mental health conditions and provides standardised descriptions for them. It also monitors the incidence and prevalence rate of physical and mental concerns in the world. It is published by the most prestigious health related organization of the world i.e. World Health Organization (WHO). The ICD comes in 43 languages and is being used by the officials of the World Health Organization.

 

ICD has been designed to encourage international comparability in the compilation, dispensation, classification, interpretation and presentation of world mortality statistics. This also provides a format for reporting the causes of death for making the death certificates. Further, the conditions reported are then transformed into medical codes with the use of a classification structure and by the selection and amendment rules which are present in the applicable revision of the ICD which is also published by the World Health Organization. These coding rules are provided to improve on the efficacy of mortality statistics. This is done by giving preference to particular categories, by consolidating the conditions, and by selecting a certain cause of death from the reported series of conditions in a systematic manner. The single selected cause which is used for tabulation is called the underlying cause of death, and the other reported causes are the non-underlying causes of death. The amalgamation of underlying and non-underlying causes of death is then known as multiple causes of death.

 

The ICD is a global standard investigative classification for all kinds of epidemiological and health management purposes. These include the examination of general health condition of the population and the monitoring of incidence and prevalence rates of the diseases and other health problems related to other variables, like the characteristics and circumstances of the affected individuals.

 

ICD is progressively being used in research and for clinical purposes for defining the diseases and to examine the pattern of disease. It is also used for managing health care, monitoring the results and allocating resources.

 

The ICD system for reporting mortality data which is a primary indicator of health status is being used by more than 100 countries. This system is useful in monitoring the rate of diseases and deaths worldwide which is to access the progress towards Millennium Development Goals (MDGs).

 

By using ICD, the world’s health expenditures are disbursed for compensation and resource allocation. The 11th revision process is in progress and the ICD-11 will release in 2018.

 

Historical development

 

The classification of diseases goes back to 1600s in England, where John Graunt made an attempt to learn the statistics of disease. But his data lacked statistics on mortality data by age and he estimated on information which he did not gather. However, Graunt’s work contributed to some extent in medical progress.

 

During 1800s, William Farr also tried to form a better, more uniform categorization of diseases. At that time, diseases were repeatedly described imprecisely or called by a variety of names, and he attempted to identify the significance of naming and describing disease in an organized manner. The disease classification developed by Farr was ultimately adopted by the International Statistical Congress, and later on it was known as the International List of Causes of Death.

 

The classification of diseases was evolving continuously. Florence took Farr’s help to improve on the data available on the statistics of illness and causes of death. By the year 1933, the United States had started to compile an annual mortality statistics for the whole nation. In 1948, WHO adopted the ‘Manual of the International Statistical Classification of Diseases, Injuries, and Causes of Death’ which marked the commencement of international collaboration in the sphere of health statistics. This led to establishment of national committees on health statistics in several countries around the world. This provided a link between these national institutions and World Health Organization.

 

Currently, the ICD-10 is being in use on international level by physicians, nurses, researchers, and mental health professionals to evaluate medical data and provide uniformity in the collection and classification of mortality statistics on an international level. Periodic revisions are implemented to keep the manual in compatibility with the advancement in medicine.

 

The ICD is at present the most extensively used statistical classification system for diseases in the world. Some countries like Australia, Canada, and the United States have designed adaptations of ICD for their own country respectively. These manuals consist of numerous procedure codes for classification of operational or diagnostic processes.

 

Basic structure and principles of ICD

 

The ICD contains a depiction of all recognized diseases and injuries. Each disease is comprehensive with its diagnostic features and is given a unique identification code which is used to code mortality and morbidity data for death certificates and from patients and clinical records respectively.

 

The major parts of the ICD-10 utilize a single list of combination of four character codes (alphanumeric-character codes) from A00.0 to Z99.0. The premier letter of this code designate different chapter. In total, there are twenty two chapters, so several letters can be included together in one single chapter. Within each chapter, four character codes are categorized so that they denote variable classification axes. The last character which is the number after the decimal in the four-character code is not needed for reporting and is used in different ways.

 

A statistical categorization of diseases must be restricted to a limited number of mutually exclusive categories which enable them to include the whole array of morbid conditions. The categories have to be selected so that it facilitates the statistical study of disease. Diseases which are of public health importance or which occur frequently in population must have their own category. If this separation is not done, the assignment of categories will be in groups of different yet related diseased conditions. Therefore, every disease or illness or injury should have a defined position in the list of categories of disease. As a result, there will be some reserved categories for other and miscellaneous conditions which may not be given a particular position in the categorization in the classification of diseases.

 

The outline for classification structure has been developed on the guidelines proposed by William Farr in the 1800s. His idea was applicable for practical and epidemiological purposes. According to Farr, the statistical data on diseases and injuries must be categorised in the following way:

  • epidemic diseases
  • general diseases
  • local diseases arranged by site
  • developmental diseases
  • injuries

    This kind of categorization has been included in certain chapters of ICD-10. This structure has been there since a long time, however, it has been considered arbitrary in some ways, it is still considered as a better structure in terms of utility for epidemiological purposes in comparison to the counterparts. Epidemic diseases, general diseases, developmental disease and injuries comprise of special groups which put together the conditions which would be arranged inconveniently for population and disease based study. Local diseases arranged by site include chapters for every main body systems.

 

The differences between these chapters have useful implications in understanding the layout of the classification, for coding according to it, and for interpreting data based on it.

 

Knowledge of the rationale and structure of the ICD are significant for statisticians, health analysts as well as for coders. Precise and continuous use of the ICD depends on the right usage of all three volumes of ICD.

 

Volume 1 of the ICD consists of the classification of diseases which indicates the categories through which diagnoses are to be to be paid, facilitating their categorization and estimation for statistical purposes. It also provides a definition of the content of the classifications, subcategories and tabulation list items which the statisticians may find in statistical tables.

 

Using volume I for getting correct codes may be time-consuming and contain errors. To solve this problem, the Volume III consists of the alphabetical index which acts as a guide for the classification. The introduction of the index in Volume III also gives vital information related to its relationship with Volume I

 

Frequent statistical uses of the ICD are the choice of a particular condition from a record where more than one condition has been entered. Section 4 of volume III also contains the rules of selection in relation to data on mortality and morbidity.

 

International Nomenclature of Diseases

 

In 1970, the Council for International Organizations of Medical Sciences (CIOMS) started the preparation and research on International Nomenclature of Diseases (IND). Five volumes of IND were issued during 1972 and 1974 by CIOMS and its member organizations.

 

However, for the compilation of this nomenclature to get international recognition, it was necessary that this categorization is made a topic of consultation with organizations outside CIOMS too. For this, IND was then taken up as a joint project of CIOMS and WHO in 1975. This venture was guided by a Technical Steering Committee of representatives from both of these organizations.

 

The main objective of the IND is to provide a single name for each morbid entity. The chief criteria for choosing these names is that it should be applicable to only one disease and not repeated for any other categorization, the nomenclature should be unambiguous, self-descriptive and based on the cause of the disease. However, many of these widely used names do not fully fulfil these criteria but are being used as synonyms.

 

The IND is projected to be complementary to the ICD. The IND terminologies are given preference in ICD. The list of volumes of IND published till the year 1992 is:

  • Infectious diseases (bacterial diseases (1985), mycoses (1982), viral diseases (1983), parasitic diseases (1987))
  • Diseases of the lower respiratory tract (1979)
  • Diseases of the digestive system (1990)
  • Cardiac and vascular diseases (1989)
  • Metabolic, nutritional and endocrine disorders (1991)
  • Diseases of the kidney, the lower urinary tract, and the male genital system (1992)
  • Diseases of the female genital system (1992)

    Differences between ICD and DSM

 

The Diagnostic and Statistical Manual (DSM) which is currently in its fifth edition, provides a uniform criteria for the identification and diagnosis of mental health conditions. Before 1980, the diagnosis of mental health conditions was largely influenced by psychoanalysis. In 1980, DSM-III was published in which the American Psychiatric Association took measures for describing and classifying the mental health conditions by forming common groups and clusters of symptoms. A similarity has been seen in the layout of the recent DSM and the ICD owing to the collaborative work undertaken by the WHO and the APA. However, DSM stays there as a separate classification method for mental health disorders.

 

The ICD is very cost effective and is widely available at a low cost to a larger group of population across the world leading to widest distribution of the manual worldwide. However, there is a contradiction on the use of ICD and DSM between health care professionals, where many professionals find is unnecessary to have two different classification systems for mental health issues, while some believe that DSM is also as useful and important as ICD, because it contain information on symptoms related to mental health conditions which will be helpful in psychiatric diagnosis.

 

Versions of ICD

 

ICD-6: The ICD-6 was published in 1949. It was the first manual which was designed for reporting the morbidity rates and statistics. The International List of Causes of Death was renamed International Statistical Classification of Diseases. There was a division between code sections of injuries and the associated accidents, leading to formation of two separate chapters for injuries and their external causes. In this manual, a section on mental disorders was added for the first time which consisted of codes for mental health conditions and its morbidity.

 

ICD-7: In February 1955 in Paris, The international Conference for the Seventh Revision of the International Classification of Diseases was held under the guidance of the World Health Organization. On the recommendations of the WHO expert committee on Health Statistics, the seventh revision in the ICD saw essential changes and amendments of the errors and inconsistencies which were found in the previous version.

 

ICD-8a: the WHO convened the Eighth Revision Conference in Geneva in July 1965. In comparison to the seventh revision, this revision was considered more essential however; the basic structure of the classification and the general principle of classification of diseases remained unchanged. After the seventh and eighth revisions of ICDs were being utilized in full swing, the usage of ICD for indexing medical records at hospitals increased at a rapid pace and many countries decided on preparing a national adaptations of ICD which will provide them with detailed information on the application of ICD according to the disease and injuries which have a higher rate of occurrence in those countries. For instance, in the United States of America, some consultants were asked to study and analyse the eighth revision of ICD for estimating its applicability to a variety of users in the United States. This group made recommendations that more details must be provided for the coding of hospital and morbidity data. Then, the Advisory Committee to the Central Office on ICDA under the aides of American Hospital Association developed the required adaptation proposals which led to the publication of the ‘International Classification of Diseases, Adapted’ (ICDA). Beginning in 1968, ICDA-8a served as the foundation for coding diagnostic data for mortality and morbidity statistics in the United States.

 

ICD-9: The International Conference for the Ninth Revision of the International Classification of Diseases was also convened by the World Health Organization and was conducted in Geneva from 30th September to 6th October 1975.

 

The enormous growth of interest in ICD has led to coming up of suggestions, critiques and advices regarding the layout of ICD. Therefore, modification of classifications and introduction of special codes have been done provisionally to cater to the suggestions by the health care professionals, researchers and scientists. Some of the critiques were that a few subject areas in this classification were regarded as disoriented and improperly arranged and more details were required to make it more relevant and sensible for fields of medical and health care. This was made possible by classifying the conditions in the chapters dealing with the specific part of the body affected by the disease rather than to those chapters which were concerned with the generalized disease.

 

On the other hand, there were representations from countries and areas which considered such detailed classification were unnecessary and irrelevant but they needed an adaptation of a classification of ICD for their country for assessment of progress of their country in health care and disease control.

 

The final proposal of the ninth revision was accepted by the Conference in 1978. The basic structure of ICD was retained and some details were added regarding the four digit subcategories and a five digit subdivision was made optional.

 

The Ninth revision consists of an alternative method for classification of diagnostic statements which include information on general diseases and manifestation of disease in a specific organ. This will provide the users an additional advantage of producing indexes and statistics for medical care. This system is referred as the dagger and asterisk system and has been taken in the Tenth Revision also. Various technical innovations have been added to Ninth Revision so that it can be used more often in variety of situations.

 

The Ninth revision was eventually replaced by the ICD-10. The ICD-10 version is currently in use by the WHO and most countries worldwide.

 

ICD-10: Developmental Work on ICD-10 started in the year 1983. The Tenth revision was certified by the 43rd World Health Assembly in May 1990 and it came into use in WHO from 1994. The latest classification system permits more than 155000 distinct codes and allows the tracking of a variety of novel diagnoses and procedures. This is an important expansion from the ICD-9 where only 17,000 codes were available for classification. The ICD-10 was adopted by many countries in the world very swiftly. WHO managed to put several materials of ICD-10 online so that the users can have an easy access to the manual, training guidelines and files which could be easily downloaded. ICD-10-AM and ICD-10-CA have been used by Australia and New Zealand and Canada respectively. ICD-10-AM (Australia and New Zealand), ICD-10-CA (Canada), ICD-10-CM (US) and many more are the country-specific adaptations of the ICD.

 

Uses of ICD

 

Each country which has adopted ICD uses it for various aspects based on the availability of data on disease and injuries. Majorly, most of the countries utilize the entire ICD system whereas some use the ICD in hospitals or for assessment of morbidity only.

 

The Unites States’ Department of Health and Human Services felt the need for improvising the ICD so that it provides better clinical information. They developed under the ninth revision of ICD, a clinical modification manual i.e. ICD-10-CM. These clinical manifestation codes were relatively accurate and provided stronger analysis. This version was extensively being used by the hospitals and health care facilities for reporting morbidity. In 2015, the ICD-9-CM was replaced by the newer version ICD-10-CM.

 

The ICD is used for the classification of diseases and other health anomalies which have been recorded on various health and clinical record sheets and database. Originally, the ICD was used to classify the probable causes of mortality which were recorded at the time of the registration of death in the death certificates. Later on the scope of ICD extended to inclusion of diagnoses in morbidity as well. It is important to note that, although the ulterior motive of deigning the ICD has been to classify diseases and injuries with a recognized diagnosis, not every problem or issue for coming into contact with the health services may be classified in this manner. As a result, the ICD facilitates for a wide range of signs, symptoms, abnormal results, complaints and social situations which may arise in the position of a diagnosis on health-related records. Therefore, the ICD can be used for classification of data which is recorded under the sub-categories such as ‘diagnosis’, ‘reason for admission’, ‘conditions treated’ and ‘reason for consultation’. These sub-categorizations may appear on a wide range of health records using which statistics and other health related information can be derived.

 

Limitations of ICD

 

The ICD is neither planned nor appropriate for indexing of distinctive clinical entities. The ICD cannot be used judiciously in the studies of financial aspects for example billing or resource allocation. Detailed information on certain specialities is lacking in the ICD. The ICD is not helpful when it comes to the description of functioning and disability as an attribute of health. Health interventions and the possible reasons for disease encounter are also missing from ICD.

 

Future prospects

 

The ICD undergoes periodic revisions to incorporate amendments to be in order with the continuous changes in the dynamic field of medicines. Although, the overall content of the ICD-9 is similar to the newer version ICD-10, there are also slight differences between these two versions. First, the ICD-10 consists of three volumes while ICD-9 is a two-volume set. Another difference is that the ICD-10 contains alphanumeric categories while the ICD-9 has numeric categories. Third, some chapters have been reorganized, several titles have been renamed and a few conditions have been regrouped in ICD-10.  Fourth, the number of categories in ICD-10 has almost doubled relative to the categories in ICD-9. Fifth, moderately minor changes in the coding rules for mortality have been done.

 

ICD-11: The World Health Organization is at present preparing for the Eleventh revision of the International Classification of Diseases. The progress is going on at an internet-based workspace, known as the iCAT (Collaborative Authoring Tool) Platform which is similar to a wiki; however, iCAT needs more configurations and has a peer review process. Through this platform, the WHO collaborates with other interested parties in this project.

 

The final draft of the ICD-11 classification system is expected for submitted to World Health Assembly (WHA) for official approval by 2017. A review of the primary draft was completed in April 2015 and the final version, ICD-11 will be launched by 2018, after the approval of the final draft by the WHA.

 

The ICD-11 will include definitions of all the listed disease entities. These definitions will provide main description and direction on the meaning of the category in human readable terms, so that it is easy for the users to understand and apply these classifications in a practical scenario. This is advantageous as the previous version only contained title headings but no descriptions. ICD-11 with the definitions will be more subjective and add up to the understanding of the users in a comprehensive way. Each definition will have a uniform structure based on a template. The definition will consist of two parts: a standard definition template and a content model. All the features will be exemplified in the content model. The Content Model is a well organized framework which captures the knowledge that justifies the definition of a listed disease entity in ICD and allows computerization. Each ICD entity can be viewed from diverse parameters. In this version, there will be 13 defined parameters included in the Content model to describe particular categories in the ICD. These are:

  • ICD Entity Title – Fully Specified Name
  • Classification Properties – disease, disorder, injury, etc.
  • Textual Definitions – a brief standard depiction
  • Terms – synonyms of the terms, other inclusion and exclusions
  • Body System/Structure Description – anatomy and physiology
  • Temporal Properties – acute, chronic or other
  • Severity of Subtypes Properties – mild, moderate, severe, or other scales
  • Manifestation Properties – signs, symptoms
  • Causal Properties – etiology: infectious, external cause, etc.
  • Functioning Properties – impact on daily life: activities and participation
  • Specific Condition Properties – relates to pregnancy etc.
  • Treatment Properties – specific treatment considerations: e.g. resistance
  • Diagnostic Criteria – operational definitions for assessment

   ICD-11 portrays to have a more refined architecture than its older versions and is consistent with the current generation of users as a digital resource. The core of the system is referred to as the Foundation Component. It is a semantic arrangement of words and terms, where several given terms may have more than one parent. To tackle the prerequisite which statistical classifications display, the ICD-11 assists the serialization of the Foundation Component into a random number of linearization which has been optimized for use cases. The main linearization that is currently called the Joint Linearization for Morbidity and Mortality Statistics is a tabular format with which most conventional users will become familiar.

 

Summary

 

It is indicative through the above module that ICD is a diagnostic tool which is used as a global standard for investigative classification. It is used for epidemiological as well as health management purposes. The ICD has been a brainchild of WHO and is extensively used by the officials there. Currently, the ICD is available in 43 languages and is being used in more than 100 countries globally. On the basis of the critiques and suggestions by the researchers, doctors, medical professionals, the ICD undergoes periodic revisions. The revisions reflect the progress in health science and medical practice. The ICD is constantly looking for suggestions from people from varied disciplines because it develops a diverse health perspective, the knowledge from varied fields will help in building a better classification which will be inclusive. The shared process will lead to a global consensus on how diseases and health-related problems are defined and recorded. ICD is a chance to be part of international collaboration that will lead to more consistent and systematic collection of health information.

you can view video on International classification of diseases and causes of death

 

References

  • History of the development of the ICD. Available from: http://www.who.int/classifications/icd/en/HistoryOfICD.pdf, accessed on May 7, 2017.
  • https://www.britannica.com/topic/International-Classification-of-Diseases, accessed on May 7, 2017.
  • https://www.cdc.gov/nchs/icd/icd10.htm, accessed on May 7, 2017.
  • ICD vs. DSM. (2009). American Psychological Association, 40(9), p. 63. Available from: http://www.apa.org/monitor/2009/10/icd-dsm.aspx, accessed on May 8, 2017.
  • International Classification of Diseases (ICD). World Health Organization. Available from http://www.who.int/classifications/icd/en, accessed on May7, 2017.
  • International Classification of Diseases, 10th Revision (ICD-10). Available from http://www.cdc.gov/nchs/data/dvs/icd10fct.pdf, Accessed on May 7, 2017.
  • www.goodtherapy.org/blog/psychpedia/international-classification-of-diseases, accessed on May 8, 2017.

    Suggested Readings

  • International Statistical Institute. 1940. International list of causes of death. Hague: International Statistical Institute.
  • World Health Organization. 1949. Manual of the international statistical classification of diseases, injuries, and causes of death. Sixth revision. Geneva: World Health Organization