Resource

Unlikely that will be able to draft a 'tidy' mapping to the exact same set of 9 categories, such that if Observation.code, .method, .bodySite and .type are all known then .category can be computed.

Observation.code

https://www.hl7.org/fhir/valueset-observation-codes.html#expansion

<<363787002|Observable entity|

Observation.Value.valueCodeableConcept

<<362981000|Qualifier value|

MINUS <valueset for Observation.Interpretation> ?

LB: why not also members from <<441742003 Evaluation finding

JC: Because they decompose (in theory) into an Observable+Qualifier pair

Observation.dataAbsentReason

DataAbsentReason (Extensible)

HL7 Code	Definition	SNOMED CT
unknown	The value is expected to exist but is not known.
asked-unknown	The source was asked but does not know the value.
temp-unknown	There is reason to expect (from the workflow) that the value may become known.
not-asked	The workflow didn't lead to this value being known.
asked-declined	The source was asked but declined to answer.
masked	The information is not available due to security, privacy or related reasons.
not-applicable	There is no proper value for this element (e.g. last menstrual period for a male).
unsupported	The source system wasn't capable of supporting this element.
as-text	The content of the data is represented in the resource narrative.
error	Some system or workflow process error means that the information is not available.
not-a-number	The numeric value is undefined or unrepresentable due to a floating point processing error.
negative-infinity	The numeric value is excessively low and unrepresentable due to a floating point processing error.
positive-infinity	The numeric value is excessively high and unrepresentable due to a floating point processing error.
not-performed	The value is not available because the observation procedure (test, etc.) was not performed.
not-permitted	The value is not permitted in this context (e.g. due to profiles, or the base data types).

Observation.interpretation

Observation Interpretation Codes (Extensible)

HL7 Code	HL7 Code Display	SNOMED CT
_GeneticObservationInterpretation
CAR	Carrier	29679002\|Carrier of disorder\|
_ObservationInterpretationChange
B	Better	385425000\|Improved\|
D	Significant change down	442474009\|Decreased relative to previous\|
U	Significant change up	442387004\|Increased relative to previous\|
W	Worse	231877006\|Worse\|
_ObservationInterpretationExceptions
<	Off scale low
>	Off scale high
IE	Insufficient evidence
_ObservationInterpretationNormality
A	Abnormal	263654008\|Abnormal\|
AA	Critical abnormal
HH	Critical high
LL	Critical low
H	High
HU	Significantly high
L	Low
LU	Significantly low
N	Normal	17621005\|Normal\|
_ObservationInterpretationSusceptibility
I	Intermediate	264841006\|Intermediately susceptible\|
NCL	No CLSI defined breakpoint
NS	Non-susceptible
R	Resistant	30714006\|Resistant\|
SYN-R	Synergy - resistant
S	Susceptible	131196009\|Susceptible\|
SDD	Susceptible-dose dependent
SYN-S	Synergy - susceptible
EX	outside threshold	394844007\|Outside reference range\|
HX	above high threshold	281302008\|Above reference range\|
LX	below low threshold	281300000\|Below reference range\|
ObservationInterpretationDetection
IND	Indeterminate	82334004\|Indeterminate\|
E	Equivocal	42425007\|Equivocal\|
NEG	Negative	260385009\|Negative\|
ND	Not detected	260415000\|Not detected\|
POS	Positive	10828004\|Positive\|
DET	Detected	260373001\|Detected\|
ObservationInterpretationExpectation
EXP	Expected
UNE	Unexpected
ReactivityObservationInterpretation
NR	Non-reactive	131194007\|Non-Reactive\|
RR	Reactive	11214006\|Reactive\|
WR	Weakly reactive	117006002\|Weakly-reactive\|

HL7 valueset (n=48) is extensible, so could add new expressivity as SNOMED codes if there were any gaps in existing list ... but that existing list is already relatively matured and 'metalled' by use, so that seem an unlikely requirement. Many of the existing members of the HL7 valuelist have obvious SNOMED equivalents, so there is scope for a mapping rather than a completely separate SNOMED-only valuelist. Mapping exercise may also reveal some holes in existing SNOMED expressivity.

Observation.bodySite

SNOMED CT Body Structures (Example)

Observation.method

Observation Methods (Example)

Observation.referenceRange.type

Observation Reference Range Meaning Codes (Preferred)

Observation.referenceRange.appliesTo

Observation Reference Range Applies To Codes (Example)

Observation.component.code

LOINC Codes (Example)

Observation.component.value[x].valueCodeableConcept

Observation.component.dataAbsentReason