Publish Box goes here

Cohort Criteria

Cohort Criteria

Resolution Model

The adapter treats cohort resolution as a patient-set problem.

It first runs backend FHIR searches to identify matching patients. Then it fetches requested output resources for those patients.

Within one filter family, values are ORed. Across filter families, patient sets are intersected.

Examples:

Criteria	Meaning
condition-code=34000006,64766004	Crohn disease OR ulcerative colitis
condition-code=34000006&medication-code=386872004	Crohn disease AND infliximab
gender=female&birthdate-ge=1980-01-01	female patients born on or after 1980-01-01
observation-code=38445-3&date-ge=2024-02-01	patients with matching observation code and clinical activity on or after the date

Backend Searches

The adapter translates cohort criteria to ordinary backend searches:

Front criterion	Backend search
condition-code	Condition?code=...
medication-code	MedicationStatement?code=... and MedicationRequest?code=...
procedure-code	Procedure?code=...
observation-code	Observation?code=...
gender and birthdate*	Patient?gender=...&birthdate...
date*	date search across clinical resource endpoints
no cohort criteria	Patient search

The adapter extracts subject.reference or patient.reference values that point to Patient/{id}. Those patient IDs become the cohort.

Resource Fetching

After resolving the cohort, the adapter fetches output resources.

For each requested resource type:

• Patient is fetched by direct read: Patient/{id}
• Condition, MedicationRequest, MedicationStatement, Observation, and Procedure are fetched with subject=Patient/{id}
• AllergyIntolerance is fetched with patient=Patient/{id}
• Provenance is fetched globally, then trimmed to matching patient targets

If a resource-specific code filter is present, it is applied again while fetching that output resource. This keeps Condition.ndjson limited to the requested condition codes when a condition-code cohort was used.

Date Semantics

The source mock implements simple exact and range date matching.

The primary date per resource type is:

Resource	Date field
Patient	birthDate
Condition	onsetDateTime or recordedDate
Observation	effectiveDateTime or issued
MedicationStatement	effectiveDateTime or dateAsserted
MedicationRequest	authoredOn
Procedure	performedDateTime
AllergyIntolerance	onsetDateTime
Provenance	recorded
Encounter	period.start

The implementation compares the leading YYYY-MM-DD string. It is suitable for local prototype selection, not a complete FHIR date search implementation.