Composition
A set of healthcare-related information that is assembled together into a single logical package that provides a single coherent statement of meaning, establishes its own context and that has clinical attestation with regard to who is making the statement. A Composition defines the structure and narrative content necessary for a document. However, a Composition alone does not constitute a document. Rather, the Composition must be the first entry in a Bundle where Bundle.type=document, and any other resources referenced from Composition must be included as subsequent entries in the Bundle (for example Patient, Practitioner, Encounter, etc.).
- Schema
- Usage
- Relationships
- Background and Context
- Referenced By
Elements
Name | Required | Type | Description |
---|---|---|---|
identifier | Identifier | Version-independent identifier for the Composition DetailsA version-independent identifier for the Composition. This identifier stays constant as the composition is changed over time. Similar to ClinicalDocument/setId in CDA. See discussion in resource definition for how these relate. | |
status | ✓ | code | preliminary | final | amended | entered-in-error DetailsThe workflow/clinical status of this composition. The status is a marker for the clinical standing of the document. If a composition is marked as withdrawn, the compositions/documents in the series, or data from the composition or document series, should never be displayed to a user without being clearly marked as untrustworthy. The flag "entered-in-error" is why this element is labeled as a modifier of other elements. Some reporting work flows require that the original narrative of a final document never be altered; instead, only new narrative can be added. The composition resource has no explicit status for explicitly noting whether this business rule is in effect. This would be handled by an extension if required. |
type | ✓ | CodeableConcept | Kind of composition (LOINC if possible) DetailsSpecifies the particular kind of composition (e.g. History and Physical, Discharge Summary, Progress Note). This usually equates to the purpose of making the composition. For Composition type, LOINC is ubiquitous and strongly endorsed by HL7. Most implementation guides will require a specific LOINC code, or use LOINC as an extensible binding. |
category | CodeableConcept[] | Categorization of Composition DetailsA categorization for the type of the composition - helps for indexing and searching. This may be implied by or derived from the code specified in the Composition Type. This is a metadata field from [XDS/MHD](http://wiki.ihe.net/index.php?title=Mobile_access_to_Health_Documents_(MHD)). | |
subject | Reference<Resource> | Who and/or what the composition is about DetailsWho or what the composition is about. The composition can be about a person, (patient or healthcare practitioner), a device (e.g. a machine) or even a group of subjects (such as a document about a herd of livestock, or a set of patients that share a common exposure). For clinical documents, this is usually the patient. | |
encounter | Reference<Encounter> | Context of the Composition DetailsDescribes the clinical encounter or type of care this documentation is associated with. | |
date | ✓ | dateTime | Composition editing time DetailsThe composition editing time, when the composition was last logically changed by the author. The Last Modified Date on the composition may be after the date of the document was attested without being changed. |
author | ✓ | Reference< Practitioner | PractitionerRole | Device | Patient | RelatedPerson | Organization >[] | Who and/or what authored the composition DetailsIdentifies who is responsible for the information in the composition, not necessarily who typed it in. |
title | ✓ | string | Human Readable name/title DetailsOfficial human-readable label for the composition. For many compositions, the title is the same as the text or a display name of Composition.type (e.g. a "consultation" or "progress note"). Note that CDA does not make title mandatory, but there are no known cases where it is useful for title to be omitted, so it is mandatory here. Feedback on this requirement is welcome during the trial use period. |
confidentiality | code | As defined by affinity domain DetailsThe code specifying the level of confidentiality of the Composition. The exact use of this element, and enforcement and issues related to highly sensitive documents are out of scope for the base specification, and delegated to implementation profiles (see security section). This element is labeled as a modifier because highly confidential documents must not be treated as if they are not. | |
attester | Compositionattester[] | Attests to accuracy of composition DetailsA participant who has attested to the accuracy of the composition/document. Only list each attester once. | |
id | string | Unique id for inter-element referencing DetailsUnique id for the element within a resource (for internal references). This may be any string value that does not contain spaces. | |
extension | Extension[] | Additional content defined by implementations DetailsMay be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone. | |
modifierExtension | Extension[] | Extensions that cannot be ignored even if unrecognized DetailsMay be used to represent additional information that is not part of the basic definition of the element and that modifies the understanding of the element in which it is contained and/or the understanding of the containing element's descendants. Usually modifier elements provide negation or qualification. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Applications processing a resource are required to check for modifier extensions. Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself). There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone. | |
mode | ✓ | code | personal | professional | legal | official DetailsThe type of attestation the authenticator offers. |
time | dateTime | When the composition was attested DetailsWhen the composition was attested by the party. | |
party | Reference< Patient | RelatedPerson | Practitioner | PractitionerRole | Organization > | Who attested the composition DetailsWho attested the composition in the specified way. | |
custodian | Reference<Organization> | Organization which maintains the composition DetailsIdentifies the organization or group who is responsible for ongoing maintenance of and access to the composition/document information. This is useful when documents are derived from a composition - provides guidance for how to get the latest version of the document. This is optional because this is sometimes not known by the authoring system, and can be inferred by context. However, it is important that this information be known when working with a derived document, so providing a custodian is encouraged. | |
relatesTo | CompositionrelatesTo[] | Relationships to other compositions/documents DetailsRelationships that this composition has with other compositions or documents that already exist. A document is a version specific composition. | |
id | string | Unique id for inter-element referencing DetailsUnique id for the element within a resource (for internal references). This may be any string value that does not contain spaces. | |
extension | Extension[] | Additional content defined by implementations DetailsMay be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone. | |
modifierExtension | Extension[] | Extensions that cannot be ignored even if unrecognized DetailsMay be used to represent additional information that is not part of the basic definition of the element and that modifies the understanding of the element in which it is contained and/or the understanding of the containing element's descendants. Usually modifier elements provide negation or qualification. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Applications processing a resource are required to check for modifier extensions. Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself). There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone. | |
code | ✓ | code | replaces | transforms | signs | appends DetailsThe type of relationship that this composition has with anther composition or document. If this document appends another document, then the document cannot be fully understood without also accessing the referenced document. |
target[x] | ✓ | Identifier, Reference<Composition> | Target of the relationship DetailsThe target composition/document of this relationship. |
event | Compositionevent[] | The clinical service(s) being documented DetailsThe clinical service, such as a colonoscopy or an appendectomy, being documented. The event needs to be consistent with the type element, though can provide further information if desired. | |
id | string | Unique id for inter-element referencing DetailsUnique id for the element within a resource (for internal references). This may be any string value that does not contain spaces. | |
extension | Extension[] | Additional content defined by implementations DetailsMay be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone. | |
modifierExtension | Extension[] | Extensions that cannot be ignored even if unrecognized DetailsMay be used to represent additional information that is not part of the basic definition of the element and that modifies the understanding of the element in which it is contained and/or the understanding of the containing element's descendants. Usually modifier elements provide negation or qualification. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Applications processing a resource are required to check for modifier extensions. Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself). There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone. | |
code | CodeableConcept[] | Code(s) that apply to the event being documented DetailsThis list of codes represents the main clinical acts, such as a colonoscopy or an appendectomy, being documented. In some cases, the event is inherent in the typeCode, such as a "History and Physical Report" in which the procedure being documented is necessarily a "History and Physical" act. An event can further specialize the act inherent in the typeCode, such as where it is simply "Procedure Report" and the procedure was a "colonoscopy". If one or more eventCodes are included, they SHALL NOT conflict with the values inherent in the classCode, practiceSettingCode or typeCode, as such a conflict would create an ambiguous situation. This short list of codes is provided to be used as key words for certain types of queries. | |
period | Period | The period covered by the documentation DetailsThe period of time covered by the documentation. There is no assertion that the documentation is a complete representation for this period, only that it documents events during this time. | |
detail | Reference<Resource>[] | The event(s) being documented DetailsThe description and/or reference of the event(s) being documented. For example, this could be used to document such a colonoscopy or an appendectomy. | |
section | Compositionsection[] | Composition is broken into sections DetailsThe root of the sections that make up the composition. | |
id | string | Unique id for inter-element referencing DetailsUnique id for the element within a resource (for internal references). This may be any string value that does not contain spaces. | |
extension | Extension[] | Additional content defined by implementations DetailsMay be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone. | |
modifierExtension | Extension[] | Extensions that cannot be ignored even if unrecognized DetailsMay be used to represent additional information that is not part of the basic definition of the element and that modifies the understanding of the element in which it is contained and/or the understanding of the containing element's descendants. Usually modifier elements provide negation or qualification. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Applications processing a resource are required to check for modifier extensions. Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself). There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone. | |
title | string | Label for section (e.g. for ToC) DetailsThe label for this particular section. This will be part of the rendered content for the document, and is often used to build a table of contents. The title identifies the section for a human reader. The title must be consistent with the narrative of the resource that is the target of the section.content reference. Generally, sections SHOULD have titles, but in some documents, it is unnecessary or inappropriate. Typically, this is where a section has subsections that have their own adequately distinguishing title, or documents that only have a single section. Most Implementation Guides will make section title to be a required element. | |
code | CodeableConcept | Classification of section (recommended) DetailsA code identifying the kind of content contained within the section. This must be consistent with the section title. The code identifies the section for an automated processor of the document. This is particularly relevant when using profiles to control the structure of the document. If the section has content (instead of sub-sections), the section.code does not change the meaning or interpretation of the resource that is the content of the section in the comments for the section.code. | |
author | Reference< Practitioner | PractitionerRole | Device | Patient | RelatedPerson | Organization >[] | Who and/or what authored the section DetailsIdentifies who is responsible for the information in this section, not necessarily who typed it in. | |
focus | Reference<Resource> | Who/what the section is about, when it is not about the subject of composition DetailsThe actual focus of the section when it is not the subject of the composition, but instead represents something or someone associated with the subject such as (for a patient subject) a spouse, parent, fetus, or donor. If not focus is specified, the focus is assumed to be focus of the parent section, or, for a section in the Composition itself, the subject of the composition. Sections with a focus SHALL only include resources where the logical subject (patient, subject, focus, etc.) matches the section focus, or the resources have no logical subject (few resources). Typically, sections in a doument are about the subject of the document, whether that is a patient, or group of patients, location, or device, or whatever. For some kind of documents, some sections actually contain data about related entities. Typical examples are a section in a newborn discharge summary concerning the mother, or family history documents, with a section about each family member, though there are many other examples. | |
text | Narrative | Text summary of the section, for human interpretation DetailsA human-readable narrative that contains the attested content of the section, used to represent the content of the resource to a human. The narrative need not encode all the structured data, but is required to contain sufficient detail to make it "clinically safe" for a human to just read the narrative. Document profiles may define what content should be represented in the narrative to ensure clinical safety. | |
mode | code | working | snapshot | changes DetailsHow the entry list was prepared - whether it is a working list that is suitable for being maintained on an ongoing basis, or if it represents a snapshot of a list of items from another source, or whether it is a prepared list where items may be marked as added, modified or deleted. This element is labeled as a modifier because a change list must not be misunderstood as a complete list. | |
orderedBy | CodeableConcept | Order of section entries DetailsSpecifies the order applied to the items in the section entries. Applications SHOULD render ordered lists in the order provided, but MAY allow users to re-order based on their own preferences as well. If there is no order specified, the order is unknown, though there may still be some order. | |
entry | Reference<Resource>[] | A reference to data that supports this section DetailsA reference to the actual resource from which the narrative in the section is derived. If there are no entries in the list, an emptyReason SHOULD be provided. | |
emptyReason | CodeableConcept | Why the section is empty DetailsIf the section is empty, why the list is empty. An empty section typically has some text explaining the empty reason. The various reasons for an empty section make a significant interpretation to its interpretation. Note that this code is for use when the entire section content has been suppressed, and not for when individual items are omitted - implementers may consider using a text note or a flag on an entry in these cases. | |
section | [] | Nested Section DetailsA nested sub-section within this section. Nested sections are primarily used to help human readers navigate to particular portions of the document. |
Search Parameters
Name | Type | Description | Expression |
---|---|---|---|
date | date | Composition editing time | Composition.date |
identifier | token | Version-independent identifier for the Composition | Composition.identifier |
patient | reference | Who and/or what the composition is about | Composition.subject.where(resolve() is Patient) |
type | token | Kind of composition (LOINC if possible) | Composition.type |
attester | reference | Who attested the composition | Composition.attester.party |
author | reference | Who and/or what authored the composition | Composition.author |
category | token | Categorization of Composition | Composition.category |
confidentiality | token | As defined by affinity domain | Composition.confidentiality |
context | token | Code(s) that apply to the event being documented | Composition.event.code |
encounter | reference | Context of the Composition | Composition.encounter |
entry | reference | A reference to data that supports this section | Composition.section.entry |
period | date | The period covered by the documentation | Composition.event.period |
related-id | token | Target of the relationship | Composition.relatesTo.target as Identifier |
related-ref | reference | Target of the relationship | Composition.relatesTo.target as Reference |
section | token | Classification of section (recommended) | Composition.section.code |
status | token | preliminary | final | amended | entered-in-error | Composition.status |
subject | reference | Who and/or what the composition is about | Composition.subject |
title | string | Human Readable name/title | Composition.title |
Inherited Elements
Name | Required | Type | Description |
---|---|---|---|
id | string | Logical id of this artifact DetailsThe logical id of the resource, as used in the URL for the resource. Once assigned, this value never changes. The only time that a resource does not have an id is when it is being submitted to the server using a create operation. | |
meta | Meta | Metadata about the resource DetailsThe metadata about the resource. This is content that is maintained by the infrastructure. Changes to the content might not always be associated with version changes to the resource. | |
implicitRules | uri | A set of rules under which this content was created DetailsA reference to a set of rules that were followed when the resource was constructed, and which must be understood when processing the content. Often, this is a reference to an implementation guide that defines the special rules along with other profiles etc. Asserting this rule set restricts the content to be only understood by a limited set of trading partners. This inherently limits the usefulness of the data in the long term. However, the existing health eco-system is highly fractured, and not yet ready to define, collect, and exchange data in a generally computable sense. Wherever possible, implementers and/or specification writers should avoid using this element. Often, when used, the URL is a reference to an implementation guide that defines these special rules as part of it's narrative along with other profiles, value sets, etc. | |
language | code | Language of the resource content DetailsThe base language in which the resource is written. Language is provided to support indexing and accessibility (typically, services such as text to speech use the language tag). The html language tag in the narrative applies to the narrative. The language tag on the resource may be used to specify the language of other presentations generated from the data in the resource. Not all the content has to be in the base language. The Resource.language should not be assumed to apply to the narrative automatically. If a language is specified, it should it also be specified on the div element in the html (see rules in HTML5 for information about the relationship between xml:lang and the html lang attribute). | |
text | Narrative | Text summary of the resource, for human interpretation DetailsA human-readable narrative that contains a summary of the resource and can be used to represent the content of the resource to a human. The narrative need not encode all the structured data, but is required to contain sufficient detail to make it "clinically safe" for a human to just read the narrative. Resource definitions may define what content should be represented in the narrative to ensure clinical safety. Contained resources do not have narrative. Resources that are not contained SHOULD have a narrative. In some cases, a resource may only have text with little or no additional discrete data (as long as all minOccurs=1 elements are satisfied). This may be necessary for data from legacy systems where information is captured as a "text blob" or where text is additionally entered raw or narrated and encoded information is added later. | |
contained | Resource[] | Contained, inline Resources DetailsThese resources do not have an independent existence apart from the resource that contains them - they cannot be identified independently, and nor can they have their own independent transaction scope. This should never be done when the content can be identified properly, as once identification is lost, it is extremely difficult (and context dependent) to restore it again. Contained resources may have profiles and tags In their meta elements, but SHALL NOT have security labels. | |
extension | Extension[] | Additional content defined by implementations DetailsMay be used to represent additional information that is not part of the basic definition of the resource. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone. | |
modifierExtension | Extension[] | Extensions that cannot be ignored DetailsMay be used to represent additional information that is not part of the basic definition of the resource and that modifies the understanding of the element that contains it and/or the understanding of the containing element's descendants. Usually modifier elements provide negation or qualification. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer is allowed to define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Applications processing a resource are required to check for modifier extensions. Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself). There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone. |
A Composition is the basic structure from which FHIR Documents - immutable bundles with attested narrative - are built. A single logical composition may be associated with a series of derived documents, each of which is a frozen copy of the composition.
Note: EN 13606 uses the term "Composition" to refer to a single commit to an EHR system, and offers some common examples: a composition containing a consultation note, a progress note, a report or a letter, an investigation report, a prescription form or a set of bedside nursing observations. Using Composition for an attested EHR commit is a valid use of the Composition resource, but for FHIR purposes, it would be usual to make more granular updates with individual provenance statements.
The Clinical Document profile constrains Composition to specify a clinical document (matching CDA ). See also the comparison with CDA.
Composition is a structure for grouping information for purposes of persistence and attestability. There are several other grouping structures in FHIR with distinct purposes:
- The List resource - enumerates a flat collection of resources and provides features for managing the collection. While a particular List instance may represent a "snapshot", from a business process perspective, the notion of "list" is dynamic – items are added and removed over time. The List resource references other resources. Lists may be curated and have specific business meaning.
- The Group resource - defines a group of specific people, animals, devices, etc. by enumerating them, or by describing qualities that group members have. The Group resource refers to other resources, possibly implicitly. Groups are intended to be acted upon or observed as a whole (e.g., performing therapy on a group, calculating risk for a group, etc.). This resource will commonly be used for public health (e.g., describing an at-risk population), clinical trials (e.g., defining a test subject pool) and similar purposes.
- The Bundle resource - is an infrastructure container for a group of resources. It does not have narrative and is used to group collections of resources for transmission, persistence or processing (e.g., messages, documents, transactions, query responses, etc.). The content of bundles is typically algorithmically determined for a particular exchange or persistence purpose.
- The Composition resource - defines a set of healthcare-related information that is assembled together into a single logical document that provides a single coherent statement of meaning, establishes its own context and that has clinical attestation with regard to who is making the statement. The Composition resource provides the basic structure of a FHIR document. The full content of the document is expressed using a Bundle containing the Composition and its entries.
The Composition resource organizes clinical and administrative content into sections, each of which contains a narrative, and references other resources for supporting data. The narrative content of the various sections in a Composition are supported by the resources referenced in the section entries. The complete set of content to make up a document includes the Composition resource together with various resources pointed to or indirectly connected to the Composition, all gathered together into a Bundle for transport and persistence. Resources associated with the following list of Composition references SHALL be included in the Bundle:
- Composition.subject
- Composition.encounter
- Composition.author
- Composition.attester.party
- Composition.custodian
- Composition.event.detail
- Composition.section.author
- Composition.section.focus
- Composition.section.entry
Other resources referred to by those resources MAY be included in the Bundle at the discretion of the authoring system as documented in the system's operation definition (such as $document operation), or as specified by any applicable profiles.
Composition Status Codes
Every composition has a status element, which describes the status of the content of the composition, taken from this list of codes:
The workflow/clinical status of the composition.
preliminary | This is a preliminary composition or document (also known as initial or interim). The content may be incomplete or unverified. |
final | This version of the composition is complete and verified by an appropriate person and no further work is planned. Any subsequent updates would be on a new version of the composition. |
amended | The composition content or the referenced resources have been modified (edited or added to) subsequent to being released as "final" and the composition is complete and verified by an authorized person. |
entered-in-error | The composition or document was originally created/issued in error, and this is an amendment that marks that the entire series should not be considered as valid. |
Composition status generally only moves down through this list - it moves from preliminary
to final
and then it may progress to amended
. Note that in many workflows, only final
compositions are made available and the preliminary
status is not used.
A very few compositions are created entirely in error in the workflow - usually the composition concerns the wrong patient or is written by the wrong author, and the error is only detected after the composition has been used or documents have been derived from it. To support resolution of this case, the composition is updated to be marked as entered-in-error
and a new derived document can be created. This means that the entire series of derived documents is now considered to be created in error and systems receiving derived documents based on retracted compositions SHOULD remove data taken from earlier documents from routine use and/or take other appropriate actions. Systems are not required to provide this workflow or support documents derived from retracted compositions, but they SHALL NOT ignore a status of entered-in-error
. Note that systems that handle compositions or derived documents and don't support the error status need to define some other way of handling compositions that are created in error; while this is not a common occurrence, some clinical systems have no provision for removing erroneous information from a patient's record, and there is no way for a user to know that it is not fit for use - this is not safe.
Note for CDA aware readers
Many users of this specification are familiar with the Clinical Document Architecture (CDA) and related specifications. CDA is a primary design input to the Composition resource (other principal inputs are other HL7 document specifications and EN13606). There are three important structural differences between CDA and the Composition resource:
- A composition is a logical construct- its identifier matches to the CDA ClinicalDocument.setId. Composition resources are wrapped into Document structures, for exchange of the whole package (the composition and its parts), and this wrapped, sealed entity is equivalent to a CDA document, where the Bundle.id is equivalent in function to ClinicalDocument.id (but it is not identical when interconverting, since it's a transform between them).
- The composition section defines a section (or sub-section) of the document, but unlike CDA, the section entries are actually references to other resources that hold the supporting data content for the section. This design means that the data can be reused in many other ways.
- Unlike CDA, the context defined in the
Composition
(the confidentiality, subject, author, event, event period and encounter) apply to the composition and do not specifically apply to the resources referenced from thesection.entry
. There is no context flow model in FHIR, so each resource referenced from within aComposition
expresses its own individual context. In this way, clinical content can safely be extracted from the composition.
In addition, note that both the code lists (e.g., Composition.status) and the Composition resource are mapped to HL7 v3 and/or CDA.