MedicationStatement — detail: medication reconciliation

Declarative resource describing what a patient is taking (or has taken). Variable information source: patient self-report, pharmacy chart, Medication Therapy Management. Pivot of IHE PHARM-1 Medication Reconciliation at hospital admission/discharge.

Declarative vs prescription

MedicationStatement differs fundamentally from MedicationRequest:

• MedicationRequest — prescription act by an authorized practitioner. Carries medical liability.
• MedicationStatement — declaration that a medication is or has been taken. No medico-legal commitment. Source = patient, caregiver, pharmacist, spouse.
• MedicationDispense — effective dispense by pharmacy. Commercial/officinal act.
• MedicationAdministration — effective bedside administration. Nursing act.

Key fields

Medication reconciliation IHE PHARM-1

The IHE PHARM-1 profile (Medication Reconciliation) requires on admission:

1. Best Possible Medication History (BPMH) retrieval — typically via multiple MedicationStatement with informationSource = Patient.
2. Comparison with active prescriptions — existing MedicationRequest in shared health records.
3. Discrepancy resolution — physician confirmation, record update.
4. Documentation — Composition creation (Bundle) with reconciled MedicationStatements.

Essential for poly-medicated elderly (30% reduction in admission errors per HAS 2022).

Example: patient-reported metformin

{
  "resourceType": "MedicationStatement",
  "id": "ms-metformin-887",
  "status": "recorded",
  "category": [{
    "coding": [{
      "system": "http://terminology.hl7.org/CodeSystem/medication-statement-category",
      "code": "outpatient"
    }]
  }],
  "medication": {
    "concept": {
      "coding": [{
        "system": "http://www.whocc.no/atc",
        "code": "A10BA02",
        "display": "Metformin"
      }, {
        "system": "http://www.nlm.nih.gov/research/umls/rxnorm",
        "code": "860975",
        "display": "Metformin hydrochloride 500 MG Oral Tablet"
      }]
    }
  },
  "subject": { "reference": "Patient/marie-durand-887" },
  "effectivePeriod": {
    "start": "2024-09-01",
    "end": "2026-05-19"
  },
  "dateAsserted": "2026-05-19T10:30:00+02:00",
  "informationSource": [{
    "reference": "Patient/marie-durand-887",
    "display": "Patient self-report"
  }],
  "derivedFrom": [
    { "reference": "MedicationRequest/rx-metformin-2024-001" }
  ],
  "reason": [{
    "concept": {
      "coding": [{
        "system": "http://snomed.info/sct",
        "code": "44054006",
        "display": "Diabetes mellitus type 2"
      }]
    }
  }],
  "note": [{
    "text": "Patient confirms regular intake morning and evening since Sept 2024. No reported missed doses. Good tolerance, no GI issues."
  }],
  "dosage": [{
    "text": "1 tablet 500 mg morning and evening with meals",
    "timing": {
      "repeat": {
        "frequency": 2,
        "period": 1,
        "periodUnit": "d"
      }
    },
    "route": {
      "coding": [{ "system": "http://snomed.info/sct", "code": "26643006", "display": "Oral route" }]
    },
    "doseAndRate": [{
      "doseQuantity": { "value": 500, "unit": "mg", "system": "http://unitsofmeasure.org" }
    }]
  }]
}

Common pitfalls

• Confusion with MedicationRequest — important: MedicationStatement has no prescriptive power. Frequent error that distorts medico-legal audit.
• informationSource missing — without source, statement reliability is unknown. Always document (Patient / RelatedPerson / pharmacy).
• adherence neglected — R5 strengthened this field. "Patient reports taking" ≠ "patient effectively takes" (compliance).
• Partial reconciliation — forgetting OTC (acetaminophen, vitamins) creates dangerous blind spots for interactions.

Related resources

• MedicationStatement — overview
• MedicationRequest — detail
• MedicationDispense
• MedicationAdministration
• Medication