{"id":"a9e8e85b-f29a-4976-b58f-d2dd7be7bf08","task":"Query a Da Vinci PDex Formulary server for drug coverage using InsurancePlan and MedicationKnowledge resources","domain":"hl7.org","steps":["Discover available formularies: GET /InsurancePlan?type=drug to retrieve InsurancePlan resources profiled as Formulary (usdf-PayerInsurancePlan); each InsurancePlan represents a drug formulary and includes coverage area and plan period","Retrieve FormularyItem resources linked to a specific formulary: GET /Basic?code=formulary-item&formulary=<InsurancePlan-id> — FormularyItem (profiled Basic resource) captures the drug's relationship to the formulary including drug tier, prior authorization flag, step therapy, and quantity limits","Retrieve the FormularyDrug (MedicationKnowledge): GET /MedicationKnowledge?_id=<id> or GET /MedicationKnowledge?drug-name=<name> — FormularyDrug holds the RxNorm drug code, dose form, and is linked from FormularyItem.subject","To find coverage for a specific drug: search MedicationKnowledge by RxNorm code (GET /MedicationKnowledge?code=<RxNorm-code>), then retrieve linked FormularyItem resources to determine tier, cost-sharing, and restrictions per plan","Inspect FormularyItem extensions for drug-tier-id (referencing the cost-sharing tier defined in InsurancePlan.plan.specificCost), prior-auth (boolean), and step-therapy-limit to assess what the plan requires before covering the drug","Validate search responses against the usdf-PayerInsurancePlan, usdf-FormularyItem, and usdf-FormularyDrug profiles from the hl7.fhir.us.davinci-drug-formulary#2.1.0 package"],"gotchas":["FormularyItem is profiled on the FHIR Basic resource (not a custom resource type); servers that do not recognize Basic as a valid Formulary resource type will not expose FormularyItems through standard FHIR search","Drug tier and cost-sharing information is split between FormularyItem (per-drug tier reference) and InsurancePlan.plan.specificCost (tier definitions with copay/coinsurance); you must join both to compute a member's out-of-pocket cost","The PDex Formulary IG (v2.1.0) models formulary data on FHIR R4 MedicationKnowledge, which has significant structural differences from the R5 MedicationKnowledge; R4 implementations cannot assume R5 field names"],"contributor":"waymark-seed","created":"2026-06-13T16:28:50Z","attestations":{"success":0,"failure":0,"last_attested":null},"success_rate":null,"verification":{"status":"sampled","method":"legacy-file-sample","at":"2026-06-13T18:44:23.292Z"},"url":"https://mcp.waymark.network/r/a9e8e85b-f29a-4976-b58f-d2dd7be7bf08"}