FHIR to OMOP Mapping Question: Blood pressure systolic and diastolic with unmapped, not valid code (55284-4)

Question

There is a LOINC concept 55284-4 that appears in some FHIR resources, for example: https://syntheticmass.mitre.org/v1/fhir/Patient/0000aa42-c235-4447-8389-8a2640f44466/$everything

This code is for "Blood pressure systolic and diastolic" and is in the OMOP concept table as shown below.

This concept is not a standard concept, is not a valid concept (from OMOP's perspective) and does not have a mapping to any standard concept in OMOP.

This concept appears in the FHIR resource in the snippet shown below (from the synthmass url shown above).

What records should be created in OMOP to represent the snippet shown below?

        "resource": {
            "category": [
                {
                    "coding": [
                        {
                            "code": "vital-signs",
                            "display": "vital-signs",
                            "system": http://hl7.org/fhir/observation-category
                        }
                    ]
                }
            ],
            "code": {
                "coding": [
                    {
                        "code": "55284-4",
                        "display": "Blood Pressure",
                        "system": http://loinc.org
                    }
                ],
                "text": "Blood Pressure"
            },
            "component": [
                {
                    "code": {
                        "coding": [
                            {
                                "code": "8462-4",
                                "display": "Diastolic Blood Pressure",
                                "system": http://loinc.org
                            }
                        ],
                        "text": "Diastolic Blood Pressure"
                    },
                    "valueQuantity": {
                        "code": "mmHg",
                        "system": http://unitsofmeasure.org,
                        "unit": "mmHg",
                        "value": 84.88290301982099
                    }
                },
                {
                    "code": {
                        "coding": [
                            {
                                "code": "8480-6",
                                "display": "Systolic Blood Pressure",
                                "system": http://loinc.org
                            }
                        ],
                        "text": "Systolic Blood Pressure"
                    },
                    "valueQuantity": {
                        "code": "mmHg",
                        "system": http://unitsofmeasure.org,
                        "unit": "mmHg",
                        "value": 117.69213707496547
                    }
                }
            ],
            "context": {
                "reference": "Encounter/52430cb1-a0d3-4d1e-926c-c878c218502e"
            },
            "effectiveDateTime": "2018-05-06T04:07:24-04:00",
            "id": "186e8672-f9ac-4419-8c5d-1e824bf6e536",
            "issued": "2018-05-06T04:07:24.278-04:00",
            "meta": {
                "lastUpdated": "2019-04-09T08:36:08.363897+00:00",
                "versionId": "MTU1NDc5ODk2ODM2Mzg5NzAwMA"
            },
            "resourceType": "Observation",
            "status": "final",
            "subject": {
                "reference": "Patient/0000aa42-c235-4447-8389-8a2640f44466"
            }
        }

---

EDIT: ADDITIONAL INFORMATION It looks like these are probably commonly used concepts for blood pressure in OMOP

select 
    * 
from 
    concept 
where 1=1
    and (
        lower(concept_name) = 'systolic blood pressure' or
        lower(concept_name) = 'diastolic blood pressure')
    and domain_id = 'Measurement'
    and standard_concept = 'S';

And there are lots of other potential candidates (about 380 of them):

select 
    * 
from 
    concept 
where 1=1
    and lower(concept_name) like '%blood pressure%'
    and domain_id = 'Measurement'
    and standard_concept = 'S';

Answer 1

I would map it the same as if it was LOINC code 85354-9. However, you should file an issue with Synthea because using the code 55284-4 without also having a translation of 85354-9 is non-conformant. (All FHIR conformant systems conveying a combined 'blood pressure' Observation are required to adhere to this profile, which mandates the 85354-9 code.)