Source of information
Another recurring issue for many clinical statements is the representation of how the information in that statement was obtained (e.g. patient-reported symptom, gleaned from chart review, physical exam finding). Whether or not the source of information needs to be included in a particular communication is outside the scope of this guide, but in some cases, such as the recording of patient medications, knowing the source of the information can have significant clinical implications, and since there are overlaps in HL7 and SNOMED CT representations, the topic is addressed in this guide.
Common sources include: [1] Previously recorded information (e.g. a patient-authored questionnaire, a problem list entry,
a lab report); [2] Informant (e.g. the patient, a witness); [3] Direct examination (e.g. a physical examination finding, a
radiographic finding, an automated specimen analysis).
Various ways by which the source of information can be represented include:
- SNOMED CT defining attributes (whether pre- or post-coordinated)
- [ 418775008 | Finding method ]: Used to indicate the method by which a finding was ascertained.
-
- [ 419066007 | Finding informer ]: Used to indicate the informant of a finding.
-
- [ 260686004 | Procedure method ]: Used to indicate the method by which a procedure is performed.
-
- [ 370129005 | Measurement method ]: Used to indicate the method by which an observable entity or evaluation procedure is performed.
- RIM attributes
- Procedure.methodCode: Identifies the means or technique used to perform the procedure.
-
- Observation.methodCode: A code that provides additional detail about the means or technique used to ascertain the observation.
- RIM participants
- Informant (INF): A source of reported information.
- RIM act relationships
- Excerpt (XCRPT): The source is an excerpt from the target.
-
- Verbatim excerpt (VRXCRPT): The source is a direct quote from the target.
Patterns for the common sources listed above include:
PATTERN ONE: Source is previously recorded information.
<observation classCode="OBS" moodCode="EVN">
<id root="3568dbe1-8f49-11da-a72b-0800200c9a66"/>
<code code="ASSERTION" codeSystem="2.16.840.1.113883.5.4"/>
<text>Headache, per problem list</text>
<value xsi:type="CD" code=" 25064002|Headache|" codeSystem="2.16.840.1.113883.6.96">
<displayName value="Headache"/>
</value>
<actRelationship typeCode="XCRPT"
contextConductionInd="false">
<actReference classCode="OBS" moodCode="EVN">
<id root="201877f1-8f49-11da-a72b-0800200c9a66"/>
</actReference>
</actRelationship>
</observation>
This pattern uses an actRelationshipType of "XCRPT" to indicate that there is a new observation which represents an excerpt of previously recorded information. The ActReference class is used here as the target, but other clinical statement act choices could also be used. Context conduction to the ActReference class is blocked by setting contextConductionInd to "false".
PATTERN TWO: Source is informant.
The distinction between the excerpt relationship in the prior figure and an informant participant discussed here can be blurry,
such as when a clinician is drawing upon the patient's recollection and a prior record of medication use to determine the
current medication usage. An informant (or source of information) is a person who provides relevant information, whereas an
excerpt is a sub portion of some other act.
<observation classCode="OBS" moodCode="EVN">
<code code="ASSERTION" codeSystem="2.16.840.1.113883.5.4"/>
<text>Father says that the patient has a headache.</text>
<value xsi:type="CD" code="25064002|Headache|" codeSystem="2.16.840.1.113883.6.96">
<displayName value="Headache"/>
</value>
<informant typeCode="INF">
<relatedEntity classCode="PRS">
<code code="66839005|Father|" codeSystem="2.16.840.1.113883.6.96">
<displayName value="Father"/>
</code>
</relatedEntity>
</informant>
</observation>
<observation classCode="OBS" moodCode="EVN">
<code code="ASSERTION" codeSystem="2.16.840.1.113883.5.4"/>
<text>Father says that the patient has a headache.</text>
<value xsi:type="CD" code="25064002|Headache|:419066007|Finding informer|=66839005|Father|" codeSystem="2.16.840.1.113883.6.96"/>
</observation>
The first example uses an Informant participant to indicate that the observation is gleaned through the record subject's father, and the second example expresses the same thing using the finding informer attribute in a post-coordinated expression.
The first example is particularly useful where there is a need to identify or provide additional specifics about the informant
participant. Where both informant participant and finding informer are present, the former should be the same as or a specialization
of the latter.
<observation classCode="OBS" moodCode="EVN"> <code code="ASSERTION" codeSystem="2.16.840.1.113883.5.4"/> <text>Patient states he has a headache</text> <value xsi:type="CD" code="25064002|Heachache|:419066007|Finding informer|=116154003|Patient|" codeSystem="2.16.840.1.113883.6.96"/> </observation>
This example shows the use of the finding informer attribute to indicate that the patient is the source of the information.
It will commonly be the case that a V3 instance will assert an informant participant, which will propagate to nested observations. Therefore it won't often be necessary to directly assert a finding informer of patient.
PATTERN THREE: Source is direct examination.
<observation classCode="OBS" moodCode="EVN"> <code code="77989009|Measurement of skin fold thickness|:370129005|Measurement method|=5880005|Physical exam|" codeSystem="2.16.840.1.113883.6.96"/> <text>Skin fold thickness is 7cm</text> <value xsi:type="PQ" value="7" unit="cm"/> </observation>
This pattern uses the SNOMED CT measurement method attribute to qualify a measurement procedure concept, indicating that the observation was determined via physical exam.
<observation classCode="OBS" moodCode="EVN">
<code code="ASSERTION" codeSystem="2.16.840.1.113883.5.4"/>
<text>Hilar mass on chest CT</text>
<value xsi:type="CD" code="309530007|Hilar mass|:418775008|Finding method|=169069000|CT chest|" codeSystem="2.16.840.1.113883.6.96"/>
<actRelationship typeCode="SUBJ" contextConductionInd="false">
<observation classCode="DGIMG" moodCode="EVN">
<id root="9cc8b460-8f47-11da-a72b-0800200c9a66"/>
<code code="169069000|CT chest|" codeSystem="2.16.840.1.113883.6.96">
<displayName value="CT chest"/>
</code>
</observation>
</actRelationship>
</observation>
This pattern uses the SNOMED CT finding method attribute to qualify a finding concept, indicating that the finding was determined via CT chest. To relate the finding to the actual CT scan being observed, the example uses an act relationship of type "SUBJ", with blocked context conduction.
