Content Model - dx revision watch

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Style Guide for

the Content Model of the ICD-11 alpha draft

The "Content Model" identifies the basic characteristics needed to define any ICD concept through use of multiple parameters (e.g. Body Systems, Body Parts, Signs and Symptoms, Diagnostic Findings, Causal Properties, Temporal Properties, Severity, Functional Impact, , and Diagnostic Rules).

The possible value sets are identified to populate this database in a relational way.

Full formal population of this content model for each categoryoncept will result in an "Information Model".

Glossary in Annex

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A. Operational Guidelines for each parameter of the ICD-11 Alpha Draft Content Model

ICD Concept Title

The "Title" is the term for any ICD concept which labels the intended concept in a meaningful, unambiguous way. The title stands for:

← The name of the ICD concept

← The part of the ICD such as a chapter, block, category or sub-category.

The title is selected from existing titles in the ICD-10 (this will be the default option). The title together with its code and naming conventions designates the placement of ICD concept within the hierarchy of classification.

If a new concept is created or a change in the title is proposed, existing titles in international agreements (such as International Nomenclatures, Terminologies) will be examined and recommendations will be made by the relevant Topic Advisory Group.

As a general rule, naming conventions for traditional concepts used in previous ICD editions will be respected. If for any reason they are retired, they will be indicated accordingly and included in the inclusion terms and indexes as appropriate. Particular names such as proper nouns for diseases or syndromes should be avoided.

Textual Definition

Textual Definition: Each ICD concept will be accompanied by a written definition of its descriptive characteristics. This full text definition enables human users to understand the meaning of a concept for classification, translation and other reasons.

a. Use of existing ICD definitions: Certain ICD-10 chapters and some specialty adaptations include textual definitions (e.g. Mental Health, Neoplasms, Neurology… ) . Additionally such definitions exist in other members of the WHO Family of International Classifications such as the International Nomenclature of Diseases. These should be incorporated by default in the ICD-11 drafts for further improvement. The improvement should be made based on the definitional criteria of a category by Topic Advisory Groups according to this Content Model.

b. Writing a new textual definition: When no textual definition exists in iCAT, contributors must describe the concept clearly and concisely. There may be three different styles of approach to define a concept. These may be used in combination.

Ideally all these approaches can be combined usefully in a single textual summary.

a. Describe the underlying physiology of the disease /disorder: e.g. myocardial infarction occurs due to an ischemia in the heart muscle and lack of oxygen in the heart muscle, which may lead to the death of myocardial tissue. This generally happens due to interruption of the blood supply of the heart when a coronary artery is blocked. Underlying this blockage is generally a collection of lipids and atherosclerotic plaques.

b. Describe the characteristics such as signs symptoms and the diagnostic criteria: Myocardial infarction occurs with sudden chest pain, palpitations and sometimes without symptoms. An electrocardiogram may show pathologic Q waves or ST segment elevation and blood tests for creatine kinase may indicate rapid rise or troponin T levels may fall.

Myocardial Infarction is an ischemic disease of the heart. Basic mechanism is the lack of oxygen in the heart muscle, which may lead to the death of myocardial tissue. This generally happens due to interruption of the blood supply of the heart when a coronary artery is blocked. Underlying this blockage is generally a collection of lipids and atherosclerotic plaques.

Ideally the textual definition will be a human readable version of the machine readable content expressed in this model.

Contributors may refer to any existing set of definitions from other scientifically credible sources. Any such reference should be cited by source (e.g. Pub Med ID; ISBN, URL…). It is not compulsory to use these if they are felt to be unsatisfactory.

Terms

Synonyms: refer to alternative names for the same underlying concept. Common terms and medical jargon may be included. Synonyms are not intended to be used interchangeably with the concept title. Their main purpose is to allow users to locate the proper code within the ICD. The concept title will have precedence over synonyms for international reporting.

Synonyms will be taken from the ICD-10, International Nomenclature of Diseases or may be proposed by TAGs as a result of the web-based joint editing process.

Inclusion: Inclusion terms appear in the tabular list of the traditional print version and show users that entities are included in the relevant concept.

Exclusion: Show users the entities that should be assigned to a different ICD catego ry because of differences in meaning or terminology.

Index Terms: indicate the terms that may correspond with ICD concepts. These terms guide users to correct codes through the use of the current index of the ICD-10 (Volume 3). The current ICD-10 index consists of multiple parts (diseases, external causes, chemicals, list of tumours). In the ICD-11, these terms may be broadened with coded dictionaries of existing electronic Cause of Death systems.

By default, the current ICD-10 terms will be used in the Index in addition to terms identified by the TAGs.

WHO will collaborate with the Revision Steering Group and the TAG-HIM to develop a computerized index driven by ontology principles and multi-lingual expressions.

Clinical Description: Each ICD concept should be defined along with multiple parameters as included in this content model.

Body Systems (Physiology): The ICD has historically used body systems as an organizing principle. Traditional divisions of body systems may be seen as arbitrary as many body parts can be a part of multiple body systems (for example, tonsil infections are currently classified to the upper respiratory tract, although the tonsils are part of the immunological system). Nevertheless, such characteristics serve to facilitate the creation of meaningful subsets for coding and analysis. Therefore, it is necessary to assign most concepts to one or more body systems. This characterization must be in line with systems currently listed in the ICD-10 to ensure compatibility; to ensure this, users must choose from a list of pre-determined ICD values within iCAT.

Anatomical Site: The ICD has traditionally used the topographic location of the body where the health-related problem can be found at the most specific level relevant to the condition. This has been the starting point for assigning an ICD code. The ICD-11 should continue this approach as this definition facilitates the creation of meaningful subsets for coding and for analysis. However, no standard anatomical site terminology or ontology has been used explicitly in creation of the ICD. The ICD-11 Content Model requires to the allocation of an anatomical site. When possible, the anatomical site should be selected from SNOMED-CT via importation from BioPortal.

Signs and Symptoms: Signs refer to objective diagnostic findings of a disease or disorder, as recognized by the patient, doctor, or others. Symptoms generally refer to a subjective indication of a disease or disorder, as experienced by the patient. In the ICD-11, no distinction will be made between signs and symptoms. Incorporating signs and symptoms will help users identify the appropriate ICD category. When possible, the signs and symptoms should be selected from SNOMED-CT and LOINC via importation from BioPortal.

Severity and/or Extent: Characterization of the severity or extent of a disease/health condition has been conventionally used outside ICD for classifying subtypes. To date, terminology commonly used for severity has been quite heterogeneous and non-standard. ICD-11 attempts to formally represent the knowledge about the severity of a concept such as mild, moderate, severe, etc.; or formal representation of the progress of the condition (e.g. staging) or its spread over the body. These severity patterns may be useful for differential diagnostics, casemix, reimbursement, and quality assessment. It is required to express severity and/or extent in accepted clinical terms.

Temporal Properties: Characterization of the onset, duration or course of a disease/health condition has been used for classifying its subtypes. The terminology used for this parameter has been quite heterogeneous and non-standard. Definitions of acute, subacute, chronic or other qualifiers have varied across disease groups. ICD-11 attempts to formally represent the knowledge about the temporal relations of a concept. It is required to express such terms in absolute time units and patterns of the clinical course, if possible.

Investigations: Every type of assessment that could be used to study a particular condition.

• Should have a basket of tests/assessments that can be used, and hospital can check off which tests were used (Case-Mix purposes)

• Overlap between investigations and diagnostic criteria.

• Could be misinterpreted as being prescriptive, or confused as a WHO Guideline.

Diagnostic Criteria: refer to the evidence that is essential to assign an ICD concept. When possible, the diagnostic criteria should be selected from recognized sources, such as ICD specialty adaptations, WHO Guidelines, LOINC or SNOMED-CT.

Causal Properties, Risk Factors and Genomic Linkages

Causal Properties: identifies the necessary cause(s) that must be present for an ICD concept to occur.

Risk Factor: is a variable associated with the likelihood of an ICD concept occurring. Risk factors are correlational and not necessarily causal. (Immediate, Proximal, Distal?)

Genomic Linkages: identify necessary candidate genes and snips related to the occurrence of the ICD concept.

Functional Impact: People with health conditions may experience differences in the functioning of their body, or as a person. Most health conditions may limit the functioning of a patient. This may be part of the disease or its consequence. The functional impact of the disease enables the identification of the disability due to the disease or health condition, which is different from the severity of the ICD category. Such information is rendered in the International Classification of Functioning, Disability and Health (ICF) as body functions, or limitations in activities or participation. Using ICF B List (Body Functions) and ICF D List (Activities and Participation) will improve joint use of ICD and ICF.

Diagnostic Rules: Various extensions to ICD, in particular specialty adaptations, have expanded on the ICD categories in identifying the diagnostic rules, i.e. the way different elements in the Content Model come together to qualify for a diagnosis according to ICD. In addition various WHO guidelines have identified diagnostic rules (e.g. guidelines, criteria) that relate to reporting of mortality, morbidity or other purposes. It will be useful to integrate and formally express these algorithms in the content model. The formalism will utilize the rubrics of the Content Model and Algorithmic Logic to express how these come together to formally identify an ICD category.

Appendix: Example of a Completed Content Model

This example is to provide a guide as to how the content model could be populated. It is a draft to stimulate discussion and enable to arrive at requirements for a formal representation.

Title

Myocardial Infarction (I 21)

Textual Definition

Myocardial Infarction is an ischemic disease of the heart. Basic mechanism is the lack of oxygen in the heart muscle, which may lead to the death of myocardial tissue. This generally happens due to interruption of the blood supply of the heart when a coronary artery is blocked. Underlying this blockage is generally a collection of lipids and atherosclerotic plaques.

Synonyms

Heart attack

Acute coronary syndrome

etc.

Index Terms

Coronary (artery)(vein) embolism

Occlusion

Thromboembolism

Heart attack

Acute coronary syndrome

Exclusion/Inclusion Terms

Excludes: certain current complications following acute myocardial infarction (I23.−)

myocardial infarction:

• old (I25.2)

• specified as chronic or with a stated duration of more than 4 weeks (more than 28 days) from onset (I25.8)

• subsequent (I22.−)

• postmyocardial infarction syndrome (I24.1)

Definitional Characteristics

Type

Disease

Body Systems (Physiology)

Cardiovascular System

Body Parts (Anatomical Site)

Heart

Myocardium

Manifestation Attributes

i) Symptoms and Signs

(1) sudden chest pain (typically radiating to the left arm or left side of the neck)

(2) shortness of breath

(3) nausea or vomiting

(4) palpitations

(5) sweating

(6) anxiety (often described as a sense of impending doom)

(7) 25% are without chest pain or other symptoms " Silent MI"

ii) Diagnostic Findings

(1)an electrocardiogram (ECG, EKG): a distinction is made between ST elevation MI (STEMI) or non-ST elevation MI (NSTEMI)

(2) chest X-ray

(3) blood tests creatine kinase-MB (CK-MB) fraction

(4) troponin I (TnI) or troponin T (TnT) levels.

iii) Functional Impacts

Heart Functions (b410)

Blood Supply to the Heart (b4103)

Chest Pain (b28011)

Any Activity or Participation Restriction (d410-d999)

Etiology

i) Causal Agents

•Anoxia

•Ischemia

•Thrombosis

Embolism

ii) Mechanisms

•Basic mechanism is the lack of oxygen in the heart muscle which may lead to the death of myocardial tissue. This generally happens due to interruption of the blood supply of the heart when a coronary artery is blocked. Underlying this blockage is generally a collection of lipids and atherosclerotic plaques.

•Association of the angiotensin type 1 receptor (AT1R) +1166A/C polymorphism with MI *C allele conferred an increase in MI risk (odds ratio = 1.13 per allele, p = 0.005).



Temporal Relations

i) Temporal Patterns

Acute by default

Severity and/or Extent

(1) ST elevation MI (STEMI)

(2) non-ST elevation MI (NSTEMI)

Treatment

Most cases of STEMI are treated with thrombolysis or if possible with percutaneous coronary intervention (PCI, angioplasty and stent insertion), provided the hospital has facilities for coronary angiography. NSTEMI is managed with medication, although PCI is often performed during hospital admission.

•Sedatives

•Dilatation

•Lysis

Diagnostic Rules

Criteria for acute, evolving or recent MI

Either one of the following criteria satisfies the diagnosis for an acute, evolving or recent MI:

(1) Typical rise and gradual fall (troponin) or more rapid rise and fall (CK-MB) of biochemical markers

of myocardial necrosis with at least one of the following:

a) ischemic symptoms;

b) development of pathologic Q waves on the ECG;

c) ECG changes indicative of ischemia (ST segment elevation or depression); or

d) coronary artery intervention (e.g., coronary angioplasty).

(2) Pathologic findings of an acute MI.

Criteria for established MI

Any one of the following criteria satisfies the diagnosis for established MI:

(1) Development of new pathologic Q waves on serial ECGs. The patient may or may not remember

previous symptoms. Biochemical markers of myocardial necrosis may have normalized, depending on

the length of time that has passed since the infarct developed.

(2) Pathologic findings of a healed or healing MI.

Reference: Myocardial infarction redefined — A consensus document of The Joint European Society of Cardiology/American College of Cardiology Committee for the Redefinition of Myocardial Infarction; The Joint European Society of Cardiology/American College of Cardiology Committee European Heart Journal (2000) 21, 1502–1513 doi:10.1053/euhj.2000.2305,

available online at

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