Observation - FHIR v0.0.82

This page is part of the FHIR Specification (v0.0.82: DSTU 1). The current version which supercedes this version is 5.0.0. For a full list of available versions, see the Directory of published versions . Page versions: R5 R4B R4 R3 R2

4.15.7 Resource Observation - Formal Definitions

Formal definitions for the elements in the Observation resource.

Observation
Definition	Measurements and simple assertions made about a patient, device or other subject.
Control	1..1
Requirements	Observations are a key aspect of healthcare. This resource is used to capture those that do not require more sophisticated mechanisms.
Aliases	Vital 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.
Invariants	Defined on this element Inv-2: Can only have normal range if value is a quantity (xpath: exists(f:valueQuantity) or not(exists(f:normalRange)))
Observation.name
Definition	Describes what was observed. Sometimes this is called the observation "code".
Control	1..1
Binding	ObservationType: LOINC codes filtered to exclude panel codes (See http://hl7.org/fhir/vs/observation-codes)
Type	CodeableConcept
Requirements	Knowing what kind of observation is being made is essential to understanding the observation.
Observation.value[x]
Definition	The information determined as a result of making the observation, if the information has a simple value.
Control	0..1
Type	Quantity\|CodeableConcept\|Attachment\|Ratio\|Period\|SampledData\|string
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 store) may have both a value and related observations (for apgar, the observations from which the measure is derived). If a value is present, the datatype for this element should be determined by Observation.name. 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.name defines a coded value. 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).
To Do	Should have Range as a valid data type here.
Observation.interpretation
Definition	The assessment made based on the result of the observation.
Control	0..1
Binding	ObservationInterpretation: (See http://hl7.org/fhir/vs/observation-interpretation)
Type	CodeableConcept
Requirements	For some results, particularly numeric results, an interpretation is necessary to fully understand the significance of a result.
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.
Control	0..1
Type	string
Requirements	Need to be able to provide free text additional information.
Observation.applies[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.
Control	0..1
Type	dateTime\|Period
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	Date/Time this was made available.
Control	0..1
Type	instant
Comments	Updated when the result is updated.
Observation.status
Definition	The status of the result value.
Control	1..1
Binding	ObservationStatus: Codes providing the status of an observation (see http://hl7.org/fhir/observation-status for values)
Type	code
Is Modifier	true
Requirements	Need to track the status of individual results - some results are finalised before the whole report is finalised.
Observation.reliability
Definition	An estimate of the degree to which quality issues have impacted on the value reported.
Control	1..1
Binding	ObservationReliability: Codes that provide an estimate of the degree to which quality issues have impacted on the value of an observation (see http://hl7.org/fhir/observation-reliability for values)
Type	code
Is Modifier	true
Requirements	Not all results are completely reliable, and some are still reported anyway.
Comments	Note that in most contexts, unreliable results are not recorded, deleted, or otherwise excluded, but it's not always possible to exclude them from the record. Interpreters of a result, whether human or machine, SHALL always either be aware of the status, or prevented from using the observation without being unaware that the reliability is not "ok".
Observation.bodySite
Definition	Indicates where on the subject's body the observation was made.
Control	0..1
Binding	BodySite: SNOMED CT Body site concepts (See http://hl7.org/fhir/vs/body-site)
Type	CodeableConcept
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.name.
Observation.method
Definition	Indicates the mechanism used to perform the observation.
Control	0..1
Binding	ObservationMethod: (See http://hl7.org/fhir/vs/observation-methods)
Type	CodeableConcept
Requirements	In some cases, method can impact results and is thus for determining whether results can be compared or determining significance of results.
Comments	Only used if not implicit in code for Observation.name.
Observation.identifier
Definition	A unique identifier for the simple observation.
Control	0..1
Type	Identifier
Requirements	Allows observations to be distinguished and referenced.
Observation.subject
Definition	The thing the observation is being made about.
Control	0..1
Type	Resource(Patient \| Group \| Device \| Location)
Requirements	Observations have no value if you don't know who or what they're about.
Comments	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.
Observation.specimen
Definition	The specimen that was used when this observation was made.
Control	0..1
Type	Resource(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 are often used in contexts that track the specimen explicity (e.g. Diagnostic Report).
Observation.performer
Definition	Who was responsible for asserting the observed value as "true".
Control	0..*
Type	Resource(Practitioner \| Device \| Organization)
Requirements	May give a degree of confidence in the observation and also indicates where follow-up questions should be directed.
Comments	This would only be "Device" if the device is responsible for the measurement, not to capture the device used by a human to make the measurement. (The latter could be captured as an extension.).
Observation.referenceRange
Definition	Guidance on how to interpret the value by comparison to a normal or recommended range.
Control	0..*
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.
Invariants	Defined on this element Inv-3: Must have at least a low or a high (and no comparators) (xpath: (exists(f:low) or exists(f:high)) and not(exists(f:low/f:comparator)) and not(exists(f:high/f:comparator)))
Observation.referenceRange.low
Definition	The value of the low bound of the reference range. If this is omitted, the low bound of the reference range is assumed to be meaningless. E.g. <2.3.
Control	0..1
Type	Quantity
Comments	Do not use the comparator for < or >.
Invariants	Affect this element Inv-3: Must have at least a low or a high (and no comparators) (xpath: (exists(f:low) or exists(f:high)) and not(exists(f:low/f:comparator)) and not(exists(f:high/f:comparator)))
Observation.referenceRange.high
Definition	The value of the high bound of the reference range. If this is omitted, the high bound of the reference range is assumed to be meaningless. E.g. >5.
Control	0..1
Type	Quantity
Comments	Do not use the comparator for < or >.
Invariants	Affect this element Inv-3: Must have at least a low or a high (and no comparators) (xpath: (exists(f:low) or exists(f:high)) and not(exists(f:low/f:comparator)) and not(exists(f:high/f:comparator)))
Observation.referenceRange.meaning
Definition	Code for the meaning of the reference range.
Control	0..1
Binding	ObservationRangeMeaning: (See http://hl7.org/fhir/vs/referencerange-meaning)
Type	CodeableConcept
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.
Control	0..1
Type	Range
Requirements	Some analytes vary greatly over age.
Observation.related
Definition	Related observations - either components, or previous observations, or statements of derivation.
Control	0..*
Requirements	Some observations have important relationships to other observations (e.g Blood Pressure = systolic + diastolic), or are derived from other observations (e.g. calculated apgar score).
Comments	Normally, an observation will have either a value or a set of related observations. A few observations (e.g. apgar store) may have both a value and related observations (for apgar, the observations from which the measure is derived).
Observation.related.type
Definition	A code specifying the kind of relationship that exists with the target observation.
Control	0..1
Binding	ObservationRelationshipType: Codes specifying how two observations are related (see http://hl7.org/fhir/observation-relationshiptypes for values)
Type	code
Requirements	May need to indicate whether this observation is composed of others, or merely derived from them.
Comments	A relationship type SHOULD be provided. If the relationship type is "COMP" (composed), then the observation should not be displayed/interpreted in the absence of the related observations.
Observation.related.target
Definition	A reference to the observation that is related to this observation.
Control	1..1
Type	Resource(Observation)