Connectathon 11 Snapshot

This page is part of the FHIR Specification (v1.2.0: STU 3 Draft). The current version which supercedes this version is 5.0.0. For a full list of available versions, see the Directory of published versions

StructureDefinition: HSPC StdQtyObs Prostate specific Ag - Detailed Descriptions

Definitions for the hspc-qnlab-de-ProstateSpecificAgMCncPtSerPlasQnLabObs Profile.

Observation(hspc-stdqty)
Definition

Measurements and simple assertions made about a patient, device or other subject.

Control0..*
TypeObservation
Alternate NamesVital Signs, Measurement, Results, Tests
Comments

Used for simple observations such as device measurements, laboratory atomic results, vital signs, height, weight, smoking status, comments, etc. Other resources are used to provide context for observations such as lab reports, etc.

InvariantsDefined on this element
inv-1: Must have either a value or a dataAbsentReason but not both (xpath: (f:value or f:dataAbsentReason) and (not(f:value and f:dataAbsentReason)))
obs-6: dataAbsentReason SHALL only be present if Observation.value[x] is not present (xpath: not(exists(f:dataAbsentReason)) or (not(exists(*[starts-with(local-name(.), 'value')]))))
obs-7: Component code SHALL not be same as observation code (xpath: not(exists(f:component/f:code)) or count(for $coding in f:code/f:coding return parent::*/f:component/f:code/f:coding[f:code/@value=$coding/f:code/@value and f:system/@value=$coding/f:system/@value])=0)
Observation.id
Definition

The logical id of the resource, as used in the URL for the resource. Once assigned, this value never changes.

Control0..1
Typeid
Comments

The only time that a resource does not have an id is when it is being submitted to the server using a create operation. Bundles always have an id, though it is usually a generated UUID.

Observation.meta
Definition

The metadata about the resource. This is content that is maintained by the infrastructure. Changes to the content may not always be associated with version changes to the resource.

Control0..1
TypeMeta
Observation.implicitRules
Definition

A reference to a set of rules that were followed when the resource was constructed, and which must be understood when processing the content.

Control0..1
Typeuri
Is Modifiertrue
Comments

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 as much as possible.

Observation.language
Definition

The base language in which the resource is written.

Control0..1
BindingA human language.
The codes SHALL be taken from http://tools.ietf.org/html/bcp47
Typecode
Comments

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).

Observation.text
Definition

A human-readable narrative that contains a summary of the resource, and may 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.

Control0..1 This element is affected by the following invariants: dom-1
TypeNarrative
Alternate Namesnarrative, html, xhtml, display
Comments

Contained resources do not have narrative. Resources that are not contained SHOULD have a narrative.

Observation.contained
Definition

These 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.

Control0..*
TypeResource
Alternate Namesinline resources, anonymous resources, contained resources
Comments

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.

Observation.extension
Definition

An Extension

Control0..*
TypeExtension
SlicingThis element introduces a set of slices. The slicing rules are:
  • unordered
  • Open
  • discriminators: url
Observation.extension (http://hl7.org/fhir/StructureDefinition/hspc-reporting-priority)
Definition

the urgency level for which results must be reported to a provider or responsible individual.

Control0..1
TypeExtension (Extension Type: code)
Observation.extension (http://hl7.org/fhir/StructureDefinition/hspc-delta-flag)
Definition

Takes a value from the valueset listed in the model to indicate the data value in the containing model is a change from a previous instance of the same model.

Control0..1
TypeExtension (Extension Type: code)
Comments

This model is intended to constrain values from OBX-8 in a lab result HL7 message. Because OBX-8 is overloaded to contain multiple types of data, we need a way to tell which kind of code is sent (abnormal flag, delta flag, or ordinal interpretation.

Observation.extension (http://hl7.org/fhir/StructureDefinition/hspc-verified)
Definition

Whether the information in the element that contains this extension has been verified with the source.

Control0..1
TypeExtension (Extension Type: boolean)
Observation.extension (http://hl7.org/fhir/StructureDefinition/hspc-updated)
Definition

When this information in the element that contains this extension was last updated.

Control0..1
TypeExtension (Extension Type: dateTime)
Observation.extension (http://hl7.org/fhir/StructureDefinition/observation-focal-subject)
Definition

The focus of an observation when not the patient of record (i.e different from Observation.subject). For example, the focal subject may be a fetus, or a donor.

Control0..1
TypeExtension (Extension Type: CodeableConcept)
Comments

Use Observation.specimen element to describe the specimen. Only used if not implicit in code found in Observation.code.

Observation.modifierExtension
Definition

May 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. Usually modifier elements provide negation or qualification. In order 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.

Control0..*
TypeExtension
Is Modifiertrue
Alternate Namesextensions, user content
Comments

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.

Observation.identifier
Definition

A unique identifier for the simple observation instance.

Control0..0
TypeIdentifier
Requirements

Allows observations to be distinguished and referenced.

Comments

Not in the CEM? Does this make sense?

Observation.status
Definition

The status of the result value.

Control1..1
BindingCodes providing the status of an observation.
The codes SHALL be taken from ObservationStatus
Typecode
Is Modifiertrue
Requirements

Need to track the status of individual results. Some results are finalized before the whole report is finalized.

Observation.category
Definition

A code that classifies the general type of observation being made. This is used for searching, sorting and display purposes.

Control0..1
BindingCodes for high level observation categories .
For example codes, see Observation Category Codes
TypeCodeableConcept
Comments

The level of granularity is defined by the category concepts in the value set. More fine-grained filtering can be performed using the metadata and/or terminology hierarchy in Observation.code.

Observation.code
Definition

Describes what was observed. Sometimes this is called the observation "name".

Control1..1
BindingStandard LOINC codes
The codes SHOULD be taken from HSPC Quantitative Labs
TypeCodeableConcept
Requirements

Knowing what kind of observation is being made is essential to understanding the observation.

Fixed Value<valueCodeableConcept xmlns="http://hl7.org/fhir">
  <coding>
    <system value="http://loinc.org"/>
    <code value="2857-1"/>
  </coding>
</valueCodeableConcept>
Observation.subject
Definition

The patient, or group of patients, location, or device whose characteristics (direct or indirect) are described by the observation and into whose record the observation is placed. Comments: Indirect characteristics may be those of a specimen, fetus, donor, other observer (for example a relative or EMT), or any observation made about the subject.

Control1..1
TypeChoice of: Reference(Patient), Reference(Group), Reference(Device), Reference(Location)
Requirements

Observations have no value if you don't know who or what they're about.

Comments

One would expect this element to be a cardinality of 1..1. The only circumstance in which the subject can be missing is when the observation is made by a device that does not know the patient. In this case, the observation SHALL be matched to a patient through some context/channel matching technique, and at this point, the observation should be updated.

If the target of the observation is different than the subject, the general extension observation-focal-subject. may be used. However, the distinction between the patient's own value for an observation versus that of the fetus, or the donor or blood product unit, etc., are often specified in the observation code.

Observation.encounter
Definition

The healthcare event (e.g. a patient and healthcare provider interaction) during which this observation is made.

Control0..1
TypeReference(Encounter)
Requirements

For some observations it may be important to know the link between an observation and a particular encounter.

Observation.effective[x]
Definition

The time or time-period the observed value is asserted as being true. For biological subjects - e.g. human patients - this is usually called the "physiologically relevant time". This is usually either the time of the procedure or of specimen collection, but very often the source of the date/time is not known, only the date/time itself.

Control0..1
TypeChoice of: dateTime, Period
[x] NoteSee Choice of Data Types for further information about how to use [x]
Requirements

Knowing when an observation was deemed true is important to its relevance as well as determining trends.

Comments

At least a date should be present unless this observation is a historical report.

Observation.issued
Definition

The date and time this observation was made available to providers, typically after the results have been reviewed and verified.

Control0..1
Typeinstant
Comments

Updated when the result is updated.

Observation.performer
Definition

Who was responsible for asserting the observed value as "true".

Control0..*
TypeChoice of: Reference(Practitioner), Reference(Organization), Reference(Patient), Reference(RelatedPerson)
Requirements

May give a degree of confidence in the observation and also indicates where follow-up questions should be directed.

SlicingThis element introduces a set of slices. The slicing rules are:
  • ordered
  • Closed
  • discriminators: performer.type
Observation.performer(person)
Definition

the individual with the primary responsibility for the procedure or action being taken.

Control0..*
TypeReference(http://hl7.org/fhir/StructureDefinition/hspc-responsibleobserver)
Requirements

May give a degree of confidence in the observation and also indicates where follow-up questions should be directed.

Observation.performer(lab)
Definition

documents the name and address of the laboratory that performs the test. This is a CLIA required item to be printed on the report, CLIA requires the name of the laboratory, city and state of the laboratory.

Control0..1
TypeReference(http://hl7.org/fhir/StructureDefinition/hspc-performinglaboratory)
Requirements

May give a degree of confidence in the observation and also indicates where follow-up questions should be directed.

Observation.valueQuantity
Definition

The information determined as a result of making the observation, if the information has a simple value.

Control0..1
TypeQuantity
Requirements

An observation exists to have a value, though it may not if it is in error, or it represents a group of observations.

Comments

Normally, an observation will have either a value or a set of related observations. A few observations (e.g. Apgar score) may have both a value and related observations (for an Apgar score, the observations from which the measure is derived). If a value is present, the datatype for this element should be determined by Observation.code. This element has a variable name depending on the type as follows: valueQuantity, valueCodeableConcept, valueString, valueRange, valueRatio, valueSampledData, valueAttachment, valueTime, valueDateTime, or valuePeriod. (The name format is "'value' + the type name" with a capital on the first letter of the type).

If the data element is usually coded or if the type associated with the Observation.value defines a coded value, use CodeableConcept instead of string datatype even if the value is uncoded text. A value set is bound to the ValueCodeableConcept element. For boolean values use valueCodeableConcept and select codes from HL7 Version 2 Table 0136. These "yes/no" concepts can be mapped to the display name "true/false" or other mutually exclusive terms that may be needed. For further discussion and examples see the notes section below.

Observation.valueQuantity.id
Definition

unique id for the element within a resource (for internal references).

Control0..1
Typeid
Observation.valueQuantity.extension
Definition

May be used to represent additional information that is not part of the basic definition of the element. In order 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.

Control0..*
TypeExtension
Alternate Namesextensions, user content
Comments

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.

Observation.valueQuantity.value
Definition

The value of the measured amount. The value includes an implicit precision in the presentation of the value.

Control1..1
Typedecimal
Requirements

Precision is handled implicitly in almost all cases of measurement.

Comments

The implicit precision in the value should always be honored. Monetary values have their own rules for handling precision (refer to standard accounting text books).

Observation.valueQuantity.comparator
Definition

How the value should be understood and represented - whether the actual value is greater or less than the stated value due to measurement issues; e.g. if the comparator is "<" , then the real value is < stated value.

Control0..1
BindingHow the Quantity should be understood and represented.
The codes SHALL be taken from QuantityComparator
Typecode
Is Modifiertrue
Requirements

Need a framework for handling measures where the value is <5ug/L or >400mg/L due to the limitations of measuring methodology.

Comments

This is labeled as "Is Modifier" because the comparator modifies the interpretation of the value significantly. If there is no comparator, then there is no modification of the value.

Meaning if MissingIf there is no comparator, then there is no modification of the value
Observation.valueQuantity.unit
Definition

A human-readable form of the unit.

Control1..1
Typestring
Requirements

There are many representations for units of measure and in many contexts, particular representations are fixed and required. I.e. mcg for micrograms.

Observation.valueQuantity.system
Definition

The identification of the system that provides the coded form of the unit.

Control1..1 This element is affected by the following invariants: qty-3
Typeuri
Requirements

Need to know the system that defines the coded form of the unit.

Fixed Valuehttp://unitsofmeasure.org
Observation.valueQuantity.code
Definition

A computer processable form of the unit in some unit representation system.

Control1..1
Typecode
Requirements

Need a computable form of the unit that is fixed across all forms. UCUM provides this for quantities, but SNOMED CT provides many units of interest.

Comments

The UCUM code must be comparable to the LOINC example UCUM code (e.g. the UCUM definitions allow for it to be converted).

Observation.dataAbsentReason
Definition

Provides a reason why the expected value in the element Observation.value[x] is missing.

Control0..1 This element is affected by the following invariants: obs-6
BindingCodes specifying why the result (Observation.value[x]) is missing.
The codes SHALL be taken from Observation Value Absent Reason; other codes may be used where these codes are not suitable
TypeCodeableConcept
Requirements

For many results it is necessary to handle exceptional values in measurements.

Comments

Null or exceptional values can be represented two ways in FHIR Observations. One way is to simply include them in the value set and represent the exceptions in the value. For example, measurement values for a serology test could be "detected", "not detected", "inconclusive", or "specimen unsatisfactory". The alternate way is to use the value element for actual observations and use the explicit dataAbsentReason element to record exceptional values. For example, the dataAbsentReason code "error" could be used when the measurement was not completed. Because of these options, use-case agreements are required to interpret general observations for exceptional values.

Observation.interpretation
Definition

The assessment made based on the result of the observation. Intended as a simple compact code often placed adjacent to the result value in reports and flow sheets to signal the meaning/normalcy status of the result. Otherwise known as abnormal flag.

Control0..1
BindingThe set of codes that describe in what way a lab value is abnormal
The codes SHOULD be taken from Abnormal Interpretation Numeric Nom
TypeCodeableConcept
Requirements

For some results, particularly numeric results, an interpretation is necessary to fully understand the significance of a result.

Alternate NamesAbnormal Flag
Observation.comments
Definition

May include statements about significant, unexpected or unreliable values, or information about the source of the value where this may be relevant to the interpretation of the result.

Control0..1
Typestring
Requirements

Need to be able to provide free text additional information.

Comments

In the CEM, there are multiple comments. Here, they are collapsed into a single string field. TODO: is that a problem?

Observation.bodySite
Definition

Indicates the site on the subject's body where the observation was made (i.e. the target site).

Control0..0
BindingCodes describing anatomical locations. May include laterality.
For example codes, see SNOMED CT Body Structures
TypeCodeableConcept
Requirements

Knowing where the observation is made is important for tracking if multiple sites are possible.

Comments

Only used if not implicit in code found in Observation.code. If the use case requires BodySite to be handled as a separate resource instead of an inline coded element (e.g. to identify and track separately) then use the standard extension body-site-instance.

Observation.method
Definition

Indicates the mechanism used to perform the observation.

Control0..0
BindingMethods for simple observations.
For example codes, see Observation Methods
TypeCodeableConcept
Requirements

In some cases, method can impact results and is thus used for determining whether results can be compared or determining significance of results.

Comments

The method must be specified in the Observation.name.

Observation.specimen
Definition

The specimen that was used when this observation was made.

Control0..1
TypeReference(http://hl7.org/fhir/StructureDefinition/hspc-specimen)
Comments

Observations are not made on specimens themselves; they are made on a subject, but usually by the means of a specimen. Note that although specimens are often involved, they are not always tracked and reported explicitly. Also note that observation resources may be used in contexts that track the specimen explicitly (e.g. Diagnostic Report).

Observation.device
Definition

The device used to generate the observation data.

Control0..1
TypeChoice of: Reference(Device), Reference(DeviceMetric)
Comments

An extension should be used if further typing of the device is needed. Devices used to support obtaining an observation can be represented using either extension or through the Observation.related element.

Observation.referenceRange(referenceRange)
Definition

Guidance on how to interpret the value by comparison to a normal or recommended range.

Control1..1
TypeBackboneElement
Requirements

Knowing what values are considered "normal" can help evaluate the significance of a particular result. Need to be able to provide multiple reference ranges for different contexts.

Comments

Most observations only have one generic reference range. Systems MAY choose to restrict to only supplying the relevant reference range based on knowledge about the patient (e.g. specific to the patient's age, gender, weight and other factors), but this may not be possible or appropriate. Whenever more than one reference range is supplied, the differences between them SHOULD be provided in the reference range and/or age properties.

InvariantsDefined on this element
obs-3: Must have at least a low or a high or text (xpath: (exists(f:low) or exists(f:high)or exists(f:text)))
Observation.referenceRange.id
Definition

unique id for the element within a resource (for internal references).

Control0..1
Typeid
Observation.referenceRange.extension
Definition

May be used to represent additional information that is not part of the basic definition of the element. In order 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.

Control0..*
TypeExtension
Alternate Namesextensions, user content
Comments

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.

Observation.referenceRange.modifierExtension
Definition

May 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 that contains it. Usually modifier elements provide negation or qualification. In order 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.

Control0..*
TypeExtension
Is Modifiertrue
Alternate Namesextensions, user content, modifiers
Comments

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.

Observation.referenceRange.low
Definition

The value of the low bound of the reference range. The low bound of the reference range endpoint is inclusive of the value (e.g. reference range is >=5 - <=9). If the low bound is omitted, it is assumed to be meaningless (e.g. reference range is <=2.3).

Control0..0 This element is affected by the following invariants: obs-3
TypeQuantity(SimpleQuantity)
Observation.referenceRange.high
Definition

The value of the high bound of the reference range. The high bound of the reference range endpoint is inclusive of the value (e.g. reference range is >=5 - <=9). If the high bound is omitted, it is assumed to be meaningless (e.g. reference range is >= 2.3).

Control0..0 This element is affected by the following invariants: obs-3
TypeQuantity(SimpleQuantity)
Observation.referenceRange.meaning
Definition

Code for the meaning of the reference range.

Control0..0
BindingCode for the meaning of a reference range.
For example codes, see Observation Reference Range Meaning Codes
TypeCodeableConcept
Requirements

Need to be able to say what kind of reference range this is - normal, recommended, therapeutic, or perhaps what state this reference range applies to (i.e. age, hormonal cycles, etc.).

Comments

This SHOULD be populated if there is more than one range.

Observation.referenceRange.age
Definition

The age at which this reference range is applicable. This is a neonatal age (e.g. number of weeks at term) if the meaning says so.

Control0..0
TypeRange
Requirements

Some analytes vary greatly over age.

Observation.referenceRange.text
Definition

Text based reference range in an observation which may be used when a quantitative range is not appropriate for an observation. An example would be a reference value of "Negative" or a list or table of 'normals'.

Control1..1
Typestring
Observation.related
Definition

A reference to another resource (usually another Observation but could also be a QuestionnaireAnswer) whose relationship is defined by the relationship type code.

Control0..0
TypeBackboneElement
Requirements

Normally, an observation will have either a value or a set of related observations. A few observations (e.g. Apgar score) may have both a value and a set of related observations or sometimes QuestionnaireResponse from which the measure is derived.

Comments

For a discussion on the ways Observations can assembled in groups together see Notes below.

Observation.related.id
Definition

unique id for the element within a resource (for internal references).

Control0..1
Typeid
Observation.related.extension
Definition

May be used to represent additional information that is not part of the basic definition of the element. In order 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.

Control0..*
TypeExtension
Alternate Namesextensions, user content
Comments

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.

Observation.related.modifierExtension
Definition

May 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 that contains it. Usually modifier elements provide negation or qualification. In order 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.

Control0..*
TypeExtension
Is Modifiertrue
Alternate Namesextensions, user content, modifiers
Comments

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.

Observation.related.type
Definition

A code specifying the kind of relationship that exists with the target resource.

Control0..1
BindingCodes specifying how two observations are related.
The codes SHALL be taken from ObservationRelationshipType
Typecode
Requirements

A relationship type SHOULD be provided.

Comments

"derived-from" is only logical choice when referencing QuestionnaireAnswer resource.

Observation.related.target
Definition

A reference to the observation or QuestionnaireResponse resource that is related to this observation.

Control1..1
TypeChoice of: Reference(Observation), Reference(QuestionnaireResponse)
Observation.component
Definition

Some observations have multiple component observations. These component observations are expressed as separate code value pairs that share the same attributes. Examples include systolic and diastolic component observations for blood pressure measurement and multiple component observations for genetics observations.

Control0..*
TypeBackboneElement
Requirements

Component observations share the same attributes in the Observation resource as the primary observation and are always treated a part of a single observation (they are not separable). However, the reference range for the primary observation value is not inherited by the component values and is required when appropriate for each component observation.

Comments

For a discussion on the ways Observations can assembled in groups together see Notes below.

Observation.component.id
Definition

unique id for the element within a resource (for internal references).

Control0..1
Typeid
Observation.component.extension
Definition

May be used to represent additional information that is not part of the basic definition of the element. In order 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.

Control0..*
TypeExtension
Alternate Namesextensions, user content
Comments

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.

Observation.component.modifierExtension
Definition

May 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 that contains it. Usually modifier elements provide negation or qualification. In order 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.

Control0..*
TypeExtension
Is Modifiertrue
Alternate Namesextensions, user content, modifiers
Comments

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.

Observation.component.code
Definition

Describes what was observed. Sometimes this is called the observation "code".

Control1..1 This element is affected by the following invariants: obs-7
BindingCodes identifying names of simple observations.
For example codes, see LOINC Codes
TypeCodeableConcept
Requirements

Knowing what kind of observation is being made is essential to understanding the observation.

Observation.component.value[x]
Definition

The information determined as a result of making the observation, if the information has a simple value.

Control0..1
TypeChoice of: Quantity, CodeableConcept, string, Range, Ratio, SampledData, Attachment, time, dateTime, Period
[x] NoteSee Choice of Data Types for further information about how to use [x]
Requirements

An observation exists to have a value, though it may not if it is in error, or it represents a group of observations.

Comments

Normally, an observation will have either a value or a set of related observations. A few observations (e.g. Apgar score) may have both a value and related observations (for an Apgar score, the observations from which the measure is derived). If a value is present, the datatype for this element should be determined by Observation.code. A CodeableConcept with just a text would be used instead of a string if the field was usually coded, or if the type associated with the Observation.code defines a coded value. For boolean values use valueCodeableConcept and select codes from <http://hl7.org/fhir/ValueSet/v2-0136> (These "yes/no" concepts can be mapped to the display name "true/false" or other mutually exclusive terms that may be needed"). The element, Observation.value[x], has a variable name depending on the type as follows: valueQuantity, valueCodeableConcept, valueRatio, valueChoice, valuePeriod, valueSampleData, or valueString (The name format is "'value' + the type name" with a capital on the first letter of the type).

Observation.component.dataAbsentReason
Definition

Provides a reason why the expected value in the element Observation.value[x] is missing.

Control0..1 This element is affected by the following invariants: obs-6
BindingCodes specifying why the result (Observation.value[x]) is missing.
The codes SHALL be taken from Observation Value Absent Reason; other codes may be used where these codes are not suitable
TypeCodeableConcept
Requirements

For many results it is necessary to handle exceptional values in measurements.

Comments

"Null" or exceptional values can be represented two ways in FHIR Observations. One way is to simply include them in the value set and represent the exceptions in the value. For example, measurement values for a serology test could be "detected", "not detected", "inconclusive", or "test not done". The alternate way is to use the value element for actual observations and use the explicit dataAbsentReason element to record exceptional values. For example, the dataAbsentReason code "error" could be used when the measurement was not completed. Because of these options, use-case agreements are required to interpret general observations for exceptional values.

Observation.component.referenceRange
Definition

Guidance on how to interpret the value by comparison to a normal or recommended range.

Control0..*
TypeSee referenceRange
Requirements

Knowing what values are considered "normal" can help evaluate the significance of a particular result. Need to be able to provide multiple reference ranges for different contexts.

Comments

Most observations only have one generic reference range. Systems MAY choose to restrict to only supplying the relevant reference range based on knowledge about the patient (e.g. specific to the patient's age, gender, weight and other factors), but this may not be possible or appropriate. Whenever more than one reference range is supplied, the differences between them SHOULD be provided in the reference range and/or age properties.