CDS FHIR Adapter

The CdsFhirAdapter handles conversion between CDS Hooks requests/responses and HealthChain's internal Document objects. It processes FHIR data in the context of Clinical Decision Support (CDS) services, following the CDS Hooks specification.

This adapter is specifically designed for building CDS services that receive FHIR data through prefetch and return clinical decision cards.

(Full Documentation on Clinical Decision Support)

Input and Output

Input	Output	Document Access
CDSRequest	CDSResponse	Document.fhir.get_prefetch_resources(), Document.cds.cards

Document Data Access

FHIR Prefetch Resources

Data from the CDS request's prefetch field is stored in the Document.fhir.prefetch_resources attribute as a dictionary mapping prefetch keys to FHIR resources:

# After processing with adapter.parse()
doc = adapter.parse(cds_request)

# Access prefetch resources by key
patient = doc.fhir.get_prefetch_resources("patient")
conditions = doc.fhir.get_prefetch_resources("condition")
document_ref = doc.fhir.get_prefetch_resources("document")

# Access all prefetch resources
all_resources = doc.fhir.prefetch_resources
for key, resource in all_resources.items():
    print(f"Resource '{key}': {resource.resourceType}")

CDS Cards

Generated CDS cards are stored in the Document.cds.cards attribute:

# After ML processing
for card in processed_doc.cds.cards:
    print(f"Summary: {card.summary}")
    print(f"Indicator: {card.indicator}")
    print(f"Detail: {card.detail}")
    print(f"Source: {card.source}")

Document Text Extraction

When the prefetch contains a DocumentReference resource, the adapter automatically extracts the document content and stores it in Document.text:

# If prefetch contains document with base64 content
cds_request = CDSRequest(
    prefetch={
        "document": {
            "resourceType": "DocumentReference",
            "content": [{
                "attachment": {
                    "contentType": "text/plain",
                    "data": "UGF0aWVudCBkaXNjaGFyZ2Ugbm90ZXM="  # base64 encoded
                }
            }]
        }
    }
)

doc = adapter.parse(cds_request)
print(doc.text)  # "Patient discharge notes" (decoded)