R4 Draft for Comment
DiagnosticsThis page is part of the FHIR Specification (v3.2.0: R4 Ballot 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
| Orders and Observations Work Group | Maturity Level: 5 | Normative | Compartments: Device, Encounter, Patient, Practitioner, RelatedPerson |
Normative Candidate Note: This page is candidate normative content for R4 in the Observation Package. Once normative, it will lose it's Maturity Level, and breaking changes will no longer be made.
This resource has 2 operations associated with it:
| $stats | Observation Statistics |
| $lastn | Last N Observations Query |
For more information about operations, including how they are invoked, see Operations.
The Statistics operation performs a set of statistical calculations on a set of clinical measurements such as a blood pressure as stored on the server. This operation evaluates Observation resources having valueQuantity elements that have UCUM unit codes. Observations with a status of 'entered-in-error' will be excluded from the calculations.
The set of Observations is defined by 4 parameters:
subject)code and system, or coding)'duration or period)statistic)Possible statistical analyses (see StatisticsCode):
of N measurements over the stated period value of N measurements over the stated period value of N measurements over the stated period of N measurements over the stated period of N measurements over the stated period of N measurements over the stated period of N measurements over the stated period of N measurements over the stated period of N measurements over the stated period Boundary of N measurements over the stated period Boundary of N measurements over the stated period is called the Interquartile range. (IQR = Q3-Q1) Quartile deviation or Semi-interquartile range is one-half the difference between the first and the third quartiles. This Statistic code will return both a gradient and an intercept value.If successful, the operation returns an Observation resource for each code with the results of the statistical calculations as component value pairs where the component code = the statistical code. The Observation also contains the input parameters patient,code and duration parameters. If unsuccessful, an OperationOutcome with an error message will be returned.
The client can request that all the observations on which the statistics are based be returned as well, using the include parameter. If an include parameter is specified, a limit may also be specified; the sources observations are subsetted at the server's discretion if count > limit. This functionality is included with the intent of supporting graphical presentation
The official URL for this operation definition is
http://hl7.org/fhir/OperationDefinition/Observation-stats
Formal Definition (as a OperationDefinition).
URL: [base]/Observation/$stats
This is an idempotent operation
| In Parameters: | |||||
| Name | Cardinality | Type | Binding | Profile | Documentation |
| subject | 1..1 | uri | The subject of the relevant Observations, which has the value of the Observation.subject.reference. E.g. 'Patient/123'. Reference can be to an absolute URL, but servers only perform stats on their own observations | ||
| code | 0..* | string | The test code(s) upon which the statistics are being performed. Provide along with a system, or as a coding. For example, the LOINC code =
2339-0 (Glucose [Mass/volume] in Blood) will evaluate all relevant Observations with this code in | ||
| system | 0..1 | uri | The system for the code(s). Or provide a coding instead | ||
| coding | 0..* | Coding | The test code upon which the statistics are being performed, as a Coding | ||
| duration | 0..1 | decimal | The time period of interest given as hours. For example, the duration = "1" represents the last hour - the time period from on hour ago to now | ||
| period | 0..1 | Period | The time period over which the calculations to be performed, if a duration is not provided | ||
| statistic | 1..* | code | average|max|min|count The statistical operations to be performed on the relevant operations. Multiple statistics operations can be specified. These codes are defined here | ||
| include | 0..1 | boolean | Whether to return the observations on which the statistics are based | ||
| limit | 0..1 | positiveInt | If an include parameter is specified, a limit may also be specified to limit the number of source Observations returned. If the include paramter is absent or equal to "false" the limit parameter SHALL be ignored by the server | ||
| Out Parameters: | |||||
| Name | Cardinality | Type | Binding | Profile | Documentation |
| statistics | 1..* | Observation | A set of observations, one observation for each code, each containing one component for each statistic. The Observation.component.code contains the statistic, and is relative to the Observation.code and cannot be interpreted independently. The Observation will also contain a subject, effectivePeriod, and code reflecting the input parameters. The status is fixed to | ||
| source | 0..* | Observation | Source observations on which the statistics are based | ||
If modifier extensions are present in the Observation, they must be accounted for by implementers. A modifier extension may affect the observation.value in a way that it should be excluded from the from the calculations.
This operation cannot be performed on observations that the user is not authorized to see. It is assumed that the server has identified and secured the context appropriately, and can either associate the authorization context with a single patient, or determine whether the context has the rights to the nominated patient, if there is one. If there is no nominated patient (e.g. the operation is invoked at the system level) and the context is not associated with a single patient record, then the server should return an error. Specifying the relationship between the context, a user and patient records is outside the scope of this specification.
Get the average, min, max and count of a series of BP measurements for a patient (Request):
GET [base]/Observation/$stats?subject=Patient/123&code=55284-4&system=http://loinc.org&duration=1&statistic=average&statistic=min&statistic=max&statistic=count
Response:
<?xml version="1.0" encoding="UTF-8"?>
<!--
The outcome for this particular operation is 2 Observation resources - one for the diastolic (8462-4)
and one for the systolic components (8480-6), because the requested LOINC code is a panel code
-->
<Parameters xmlns="http://hl7.org/fhir">
<parameter>
<name value="statistics"/>
<resource>
<Observation>
<status value="final"/>
<code>
<coding>
<system value="http://loinc.org"/>
<code value="8480-6"/>
<display value="Systolic blood pressure"/>
</coding>
</code>
<subject>
<reference value="Patient/123"/>
</subject>
<effectivePeriod>
<start value="2016-05-25T19:26:16Z"/>
<end value="2016-05-25T20:26:16Z"/>
</effectivePeriod>
<!--The Observation.component.code is relative to the Observation.code and cannot be interpreted independently.-->
<component>
<code>
<!-- the average parameter code -->
<coding>
<system value="http://hl7.org/fhir/observation-paramcode"/>
<code value="average"/>
<display value="Average"/>
</coding>
</code>
<valueQuantity>
<value value="121.8"/>
<unit value="mmHg"/>
<system value="http://unitsofmeasure.org"/>
<code value="mm[Hg]"/>
</valueQuantity>
</component>
<component>
<!-- the max parameter code -->
<code>
<coding>
<system value="http://hl7.org/fhir/observation-paramcode"/>
<code value="max"/>
<display value="Maximum"/>
</coding>
</code>
<valueQuantity>
<value value="136"/>
<unit value="mmHg"/>
<system value="http://unitsofmeasure.org"/>
<code value="mm[Hg]"/>
</valueQuantity>
</component>
<component>
<!-- the min parameter code -->
<code>
<coding>
<system value="http://hl7.org/fhir/observation-paramcode"/>
<code value="min"/>
<display value="Minimum"/>
</coding>
</code>
<valueQuantity>
<value value="110"/>
<unit value="mmHg"/>
<system value="http://unitsofmeasure.org"/>
<code value="mm[Hg]"/>
</valueQuantity>
</component>
<component>
<!-- the count parameter code -->
<code>
<coding>
<system value="http://hl7.org/fhir/observation-paramcode"/>
<code value="count"/>
<display value="Count"/>
</coding>
</code>
<valueQuantity>
<value value="7"/>
<system value="http://unitsofmeasure.org"/>
<code value="{observations}"/>
</valueQuantity>
</component>
</Observation>
</resource>
</parameter>
<parameter>
<name value="statistics"/>
<resource>
<Observation>
<status value="final"/>
<code>
<coding>
<system value="http://loinc.org"/>
<code value="8462-4"/>
<display value="Diastolic blood pressure"/>
</coding>
</code>
<subject>
<reference value="Patient/123"/>
</subject>
<effectivePeriod>
<start value="2016-05-25T19:26:16Z"/>
<end value="2016-05-25T20:26:16Z"/>
</effectivePeriod>
<!--The Observation.component.code is relative to the Observation.code and cannot be interpreted independently.-->
<component>
<code>
<!-- the average parameter code -->
<coding>
<system value="http://hl7.org/fhir/observation-paramcode"/>
<code value="average"/>
<display value="Average"/>
</coding>
</code>
<valueQuantity>
<value value="79.7"/>
<unit value="mmHg"/>
<system value="http://unitsofmeasure.org"/>
<code value="mm[Hg]"/>
</valueQuantity>
</component>
<component>
<!-- the max parameter code -->
<code>
<coding>
<system value="http://hl7.org/fhir/observation-paramcode"/>
<code value="max"/>
<display value="Maximum"/>
</coding>
</code>
<valueQuantity>
<value value="110"/>
<unit value="mmHg"/>
<system value="http://unitsofmeasure.org"/>
<code value="mm[Hg]"/>
</valueQuantity>
</component>
<component>
<!-- the min parameter code -->
<code>
<coding>
<system value="http://hl7.org/fhir/observation-paramcode"/>
<code value="min"/>
<display value="Minimum"/>
</coding>
</code>
<valueQuantity>
<value value="56"/>
<unit value="mmHg"/>
<system value="http://unitsofmeasure.org"/>
<code value="mm[Hg]"/>
</valueQuantity>
</component>
<component>
<!-- the count parameter code -->
<code>
<coding>
<system value="http://hl7.org/fhir/observation-paramcode"/>
<code value="count"/>
<display value="Count"/>
</coding>
</code>
<valueQuantity>
<value value="7"/>
<system value="http://unitsofmeasure.org"/>
<code value="{observations}"/>
</valueQuantity>
</component>
</Observation>
</resource>
</parameter>
</Parameters>
The lastn query meets the common need for searching for the most recent or last n=number of observations for a subject. For example, retrieving the last 5 temperatures for a patient to view trends or fetching the most recent laboratory results or vitals signs. To ask a server to return the last n=number of observations, the lastn query uses the normal search parameters defined for the Observation resource. However, rather than their normal use, they are interpreted as inputs - i.e.. instead of requiring that the resources literally contain the search parameters, they are passed to a server algorithm of some kind that uses them to determine the most appropriate matches.
The request for a lastn query SHALL include:
$lastn operation parameterpatient or subject search parametercategory parameter and/or a search parameter that contains a code element in its FHIRpath expression. ( e.g., code or code-value-concept)The request for a lastn query MAY include:
The response from a lastn query is a set of observations:
Observation.codecoding.value and coding.system are the same.for example:
|Observation.code for observation a|Observation.code for observation b|Observation.code for observation c|number of groups [codes/text in each group]| |---|---|---|---| |a|b|c | 3 [a],[b],[c]| |a|b|a,c | 2 [a.c],[b]| |a|b|a,b | 1 [a,b]| |'text'|'Text'|'t e x t'|3 ['text'],['Text'],['t e x t']|
The set of returned observations should represent distinct real world observations and not the same observation with changes in status or versions. If there are no matches, the lastn query SHALL return an empty search set with no error, but may include an operation outcome with further advice.
The official URL for this operation definition is
http://hl7.org/fhir/OperationDefinition/Observation-lastn
Formal Definition (as a OperationDefinition).
URL: [base]/Observation/$lastn
This is an idempotent operation
| In Parameters: | |||||
| Name | Cardinality | Type | Binding | Profile | Documentation |
| max | 0..1 | positiveInt |
| ||
| Out Parameters: | |||||
| Name | Cardinality | Type | Binding | Profile | Documentation |
| return | 1..1 | Bundle | The set of most recent N Observations that match the lastn query search criteria. Note: as this the only out parameter, it is a resource, and it has the name 'return', the result of this operation is returned directly as a resource | ||
The key differences between this query operation and simply searching Observation using the combination of _count and _sort parameters are:
This operation cannot be performed on observations that the user is not authorized to see. It is assumed that the server has identified and secured the context appropriately, and can either associate the authorization context with a single patient, or determine whether the context has the rights to the nominated patient, if there is one. If there is no nominated patient (e.g. the operation is invoked at the system level) and the context is not associated with a single patient record, then the server should return an error. Specifying the relationship between the context, a user and patient records is outside the scope of this specification.
1): Fetch the last 3 results for all vitals for a patient 2): Fetch the last lab results for a patient 3): Fetch the last 3 blood pressures, respiratory rate and heart rates for a patient (Request):
1) GET [base]/Observation/$lastn?max=3&patient=Patient/123&category=vital-signs -------------------------------------------- 2) GET [base]/Observation/$lastn?patient=Patient/123&category=laboratory -------------------------------------------- 3) GET [base]/Observation/$lastn?max=3&patient=Patient/123&category=vital-signs&code=9279-1,8867-4,85354-9
1): A Server returns from an imaginary Last N algorithm the last 3 of 9 different vital signs observations on a patient. e.g. body temperature, body weight, body height... (truncated for readability) 2): A Server returns from an imaginary Last N algorithm the last laboratory observations for a patient. e.g. CBC Panel, UA, Chem Panel, Lipid Panel components and HbA1c, (truncated for readability) 3): A Server returns from an imaginary Last N algorithm the last 3 blood pressures, respiratory rate and heart rates for a patient as specified by code from the request. (truncated for readability) (Response):
=========================== Example 1 ============================
HTTP/1.1 200 OK
[other headers]
{
"resourceType": "Bundle",
"id": "26419249-18b3-45de-b10e-dca0b2e72b",
"meta": {
"lastUpdated": "2017-02-18T03:28:49Z"
},
"type": "searchset",
"total": 27,
// the patient temperature was being taken several times a day
"entry": [{
"fullUrl": "http://server/path/Observation/20170219-06temp",
"resource": {
"resourceType": "Observation",
"id": "20170219temp",
.. snip ...
,{
"fullUrl": "http://server/path/Observation/20170219-05temp",
"resource": {
"resourceType": "Observation",
"id": "20170218temp",
.. snip ...
}
,{
"fullUrl": "http://server/path/Observation/20170219-04temp",
"resource": {
"resourceType": "Observation",
"id": "20170217temp",
.. snip ...
},
// the patient was being weighed daily
{
"fullUrl": "http://server/path/Observation/20170219weight",
"resource": {
"resourceType": "Observation",
"id": "20170219weight",
.. snip ...
,{
"fullUrl": "http://server/path/Observation/20170218weight",
"resource": {
"resourceType": "Observation",
"id": "20170218weight",
.. snip ...
}
,{
"fullUrl": "http://server/path/Observation/20170217weight",
"resource": {
"resourceType": "Observation",
"id": "20170217weight",
.. snip ...
},
// height was recorded occasionally over the years
{
"fullUrl": "http://server/path/Observation/20170101height",
"resource": {
"resourceType": "Observation",
"id": "20170219height",
.. snip ...
,{
"fullUrl": "http://server/path/Observation/20160101height",
"resource": {
"resourceType": "Observation",
"id": "20160101height",
.. snip ...
}
,{
"fullUrl": "http://server/path/Observation/20131001height",
"resource": {
"resourceType": "Observation",
"id": "20131001height",
.. snip ...
}
]
}
----------------------------------
=========================== Example 2 ============================
HTTP/1.1 200 OK
[other headers]
{
"resourceType": "Bundle",
"id": "26419249-18b3-45de-b10e-dca0b2e72b",
"meta": {
"lastUpdated": "2017-02-18T03:28:49Z"
},
"type": "searchset",
"total": 45,
// the patient's last CBC Panel component observations
"entry": [{
"fullUrl": "http://server/path/Observation/20170219-CBCPanel-RBCs",
"resource": {
"resourceType": "Observation",
"id": "0170219-CBCPanel-RBCs",
... snip ...
"code" : {
"coding" : [
{
"system" : "http://loinc.org",
"code" : "789-8",
"display" : "RBC # Bld Auto"
}
],
"text" : "RBC # Bld Auto"
},
...snip....
},
// the rest of the patient CBC Panel components observations
{ ...snip...
},
// the patient's last UA Panel component observations
{
"fullUrl": "http://server/path/Observation/20160610-UA-Color",
"resource": {
"resourceType": "Observation",
"id": "20160610-UA-Color",
.. snip ...
"code" : {
"coding" : [
{
"system" : "http://loinc.org",
"code" : "5778-6",
"display" : "Color of Urine"
}
],
"text" : "COLOR"
},
...snip....
},
// the rest of the patient UA Panel component observations
{ ...snip...
},
// the patient's last Metabolic Panel component observations
{
"fullUrl": "http://server/path/Observation/20170219MetPanel-Sodium",
"resource": {
"resourceType": "Observation",
"id": "20170219MetPanel-Sodium",
... snip ...
"code" : {
"coding" : [
{
"system" : "http://loinc.org",
"code" : "2951-2",
"display" : "Sodium SerPl-sCnc"
}
],
"text" : "Sodium SerPl-sCnc"
},
...snip....
},
// the rest of the patient Metabolic Panel component observations
{ ...snip...
},
// the patient Lipase Panel components observations
{
"fullUrl": "http://server/path/Observation/20170219LipidPanel-Chol",
"resource": {
"resourceType": "Observation",
"id": "20170219LipidPanel-Chol",
... snip ...
"code": {
"coding": [
{
"system": "http://loinc.org",
"code": "14647-2",
"display": "Cholesterol [Moles/volume] in Serum or Plasma"
}
],
"text": "Cholesterol"
},
...snip....
},
// the patient HbA1c observation
{
"fullUrl": "http://server/path/Observation/20170219HbA1c",
"resource": {
"resourceType": "Observation",
"id": "20170219HbA1c",
... snip ...
"code": {
"coding": [
{
"system": "http://loinc.org",
"code": "4548-4",
"display": "Hemoglobin A1c/Hemoglobin.total in Blood"
}
],
"text": "HbA1c"
},
...snip....
}
]
}
----------------------------------
=========================== Example 3 ============================
HTTP/1.1 200 OK
[other headers]
{
"resourceType": "Bundle",
"id": "26419249-18b3-45de-b10e-dca0b2e72b",
"meta": {
"lastUpdated": "2017-02-18T03:28:49Z"
},
"type": "searchset",
"total": 9,
// Returns the patient's last 3 code = 9279-1 Respiratory Rate observations All from 20170219
"entry": [{
"fullUrl": "http://server/path/Observation/20170219-06RespRate",
"resource": {
"resourceType": "Observation",
"id": "20170219-06RespRate",
.. snip ...
"code": {
"coding": [
{
"system": "http://loinc.org",
"code": "9279-1",
"display": "Respiratory rate"
}
],
"text": "Respiratory rate"
},
.. snip ...
,{
"fullUrl": "http://server/path/Observation/20170219-05RespRate",
"resource": {
"resourceType": "Observation",
"id": "20170219-05RespRate",
.. snip ...
}
,{
"fullUrl": "http://server/path/Observation/20170219-04RespRate",
"resource": {
"resourceType": "Observation",
"id": "20170217-04RespRate",
.. snip ...
},
// Returns the patient's last 3 code = 8867-4 Heart Rate observations All from 20170219
// the patient was being weighed daily
{
"fullUrl": "http://server/path/Observation/20170219-06HeartRate",
"resource": {
"resourceType": "Observation",
"id": "20170219-06HeartRate",
.. snip ...
],
"code": {
"coding": [
{
"system": "http://loinc.org",
"code": "8867-4",
"display": "Heart rate"
}
],
"text": "Heart rate"
...snip...
,{
"fullUrl": "http://server/path/Observation/20170219-05HeartRate",
"resource": {
"resourceType": "Observation",
"id": "20170219-05HeartRate",
.. snip ...
}
,{
"fullUrl": "http://server/path/Observation/20170219-04HeartRate",
"resource": {
"resourceType": "Observation",
"id": "20170219-04HeartRate",
.. snip ...
},
// Returns the patient's last 3 code = 85354-9 Blood pressure systolic and diastolic All from 20170219
{
"fullUrl": "http://server/path/Observation/20170219-06BloodPressure",
"resource": {
"resourceType": "Observation",
"id": "20170219-06BloodPressure",
.. snip ...
"code": {
"coding": [
{
"system": "http://loinc.org",
"code": "85354-9",
"display": "Bood pressure panel with all children optional"
}
],
"text": "Blood pressure systolic & diastolic"
},
...snip...
"component": [
{
"code": {
"coding": [
{
"system": "http://loinc.org",
"code": "8480-6",
"display": "Systolic blood pressure"
},
{
...snip...
{
"code": {
"coding": [
{
"system": "http://loinc.org",
"code": "8462-4",
"display": "Diastolic blood pressure"
}
]
},
...snip....
,{
"fullUrl": "http://server/path/Observation/20170219-05BloodPressure",
"resource": {
"resourceType": "Observation",
"id": "20170219-05BloodPressure",
.. snip ...
}
,{
"fullUrl": "http://server/path/Observation/20170219-04BloodPressure",
"resource": {
"resourceType": "Observation",
"id": "20170219-04BloodPressure",
.. snip ...
}
]
}
®© HL7.org 2011+. FHIR Release 4 Draft for Comment (Jan-2018 v3.2.0-12885) generated on Wed, Dec 20, 2017 15:57+1100. QA Page
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