Medication Lenses

Medication data comes from four different FHIR resources: MedicationStatement, MedicationRequest, MedicationDispense, and MedicationAdministration. Zus aligns these various resources together based on their Zus-enriched codings and writes a single MedicationStatement per unique medication based on the Patient’s history.

Summary Lens

The medication resources for a patient (i.e., MedicationStatement, MedicationRequest, MedicationDispense, and MedicationAdministration), are aligned and de-duplicated by common RxNorm (or their available CodeSystem if mapping to RxNorm was not possible). Zus then writes new Lens MedicationStatement resources with a specific tag for easy identification:

"meta": {
    "tag": [
        {
            "system": "https://zusapi.com/summary",
            "code": "Common"  
        }
    ]
}

You can query for a patient's Medication Summary Lens resources by filtering on the tag, as shown below:

{{fhir_url}}/MedicationStatement?_tag=https://zusapi.com/summary|Common&patient.identifier=https://zusapi.com/fhir/identifier/universal-id|{{universal_patient_id}}

Zus determines the value for each field in the summarized resource primarily based on the value on the raw resource with the latest real-world event date. This latest real-world event date is then used to populate the DateAsserted field of the summarized resource. The derivedFrom property on the Summary Lens resource references the resources the Summary Lens was compiled from. The status field is set to active for any Summary Lens that has activity within the last 180 days or 365 days into the future, and where the latest status among the raw resources is not one of: completed, entered-in-error, stopped, or not-taken.

Active Medication Lens

Active Medication Lenses are a subset of Summary Lenses that have a status of Active. The status is set to active for any Summary Lens that has activity within the last 180 days or 365 days into the future, and where the latest status among the raw resources is not completed, entered-in-error, stopped, or not-taken. This Lens helps answer the question: “What medications is this patient most likely on currently?”

Active Medication Lenses have the following tag:

"meta": {
    "tag": [
        {
            "system": "https://zusapi.com/lens",
            "code": "ActiveMedications"
        }
    ]
}

Because Active Medication Lens resources are a subset of Summary Lenses, they also contain the summary tag.

You can query for a patient's Active Medication Lens resources by filtering on the tag, as shown below:

{{fhir_url}}/MedicationStatement?_tag=https://zusapi.com/lens|ActiveMedications&patient.identifier=https://zusapi.com/fhir/identifier/universal-id|{{universal_patient_id}}

Data Mart Access

Medication Lens data is available in the lens_rxnorm_medication_statement table in the Zus Relational Data Mart. Read more about the schema in our Data Mart documentation.