Implement CARIN Blue Button IG to expose and consume payer ExplanationOfBenefit resources for patient cost and claims transparency

Steps

1. Confirm the payer FHIR server implements the CARIN Blue Button (CARIN BB) IG by checking the CapabilityStatement for the CARIN BB profiles in the supportedProfile field
2. Authenticate using SMART App Launch (standalone or EHR launch) with patient/ExplanationOfBenefit.read and related scopes; note that CARIN BB requires SMART on FHIR v1 or v2 per the IG version
3. Search for ExplanationOfBenefit resources with GET [base]/ExplanationOfBenefit?patient=[id]&_lastUpdated=gt[date]; use _count and next-link pagination to handle large claims histories
4. Parse CARIN BB-profiled ExplanationOfBenefit resources: type.coding identifies the claim type (professional, institutional, pharmacy, oral); item[].adjudication contains allowed amount, paid amount, patient responsibility, and denial reason codes
5. Extract patient cost information from total[] (claim-level totals) and item[].adjudication[].amount for line-level detail; map adjudication category codes to human-readable labels using the CARIN BB code systems
6. Cross-reference ExplanationOfBenefit.insurance[].coverage to Coverage resources to determine the patient's plan at time of service