MII IG Symptom
2027.0.0-ballot - Germany

This page is part of the MII Implementation Guide Symptom (v2027.0.0-ballot: 2027 Ballot 1) based on FHIR (HL7® FHIR® Standard) R4. This is the current published version. For a full list of available versions, see the Directory of published versions

Profiles

FHIR profiles

Wherever possible, the work on the core data set specifications is based on international standards and terminologies. The International Patient Summary deserves particular mention here. Adaptation to the general conditions of the German health care system is achieved by using the German base profiles of HL7 Germany.

All elements of the core data set, adapted to the details and requirements of the use cases of the Medical Informatics Initiative, are described below in the form of FHIR StructureDefinitions. The necessity of adapting the FHIR profiles is explained in textual form beneath the respective profiles.

Mandatory / must-support elements

For mandatory or must-support elements, reference is made to the corresponding IPS rules, which also apply to this implementation guide.

Written during migration - review before release. This module's profiles: MII PR Symptom Observation — abstract profile for observations (symptoms, measurements, phenotypes) · MII PR Symptom Condition — abstract profile for clinical states, problems and diagnoses.

Relationship between Observation and Condition

Note: The content of this section is based on the HL7 FHIR Symptoms Implementation Guide. The development of that implementation guide is being followed closely and serves as a template for this guide.

Relationship between symptoms and diagnoses

In clinical documentation, symptoms represent the subjective evidence of a health condition, typically experienced and reported by the patient (e.g. "fatigue", "chest pain", "nausea"). Diagnoses, on the other hand, represent the clinical interpretation or determination of an underlying disease that explains one or more symptoms or findings (e.g. "pneumonia", "myocardial infarction", "anemia").

Within FHIR, these two kinds of information are represented by different but complementary resources:

Clinical concept FHIR resource Terminologies Description
Symptom Observation SNOMED CT, LOINC Captures the presence, absence, severity or characteristics of a symptom as reported by the patient or observed by a clinician.
Diagnosis Condition SNOMED CT, ICD-10, ICD-11 Represents the clinician's diagnostic conclusion or disease identification that explains one or more symptoms and findings.

Both resource types can coexist within a patient record and are frequently linked to support clinical reasoning, quality measurement and clinical decision support use cases.

Linking symptoms and diagnoses in FHIR

FHIR offers several mechanisms for establishing relationships between Observations representing symptoms and Conditions representing diagnoses.

Condition.evidence.detail

The primary mechanism for linking a Condition to supporting evidence is the Condition.evidence.detail element. This allows a Condition to reference one or more Observations (symptoms, test results or other findings) that contributed to the diagnostic conclusion.

Observation extension: associatedSymptomOrCondition

When documenting a symptom Observation, the associatedSymptomOrCondition extension can link that symptom to a known or suspected Condition to which it relates.

Conceptual model

Patient experience → Symptom (Observation) → Clinical interpretation → Diagnosis (Condition)
  • Symptoms (Observations) provide the evidence-based foundation for diagnostic reasoning.
  • Diagnoses (Conditions) represent the resulting clinical interpretation and frequently reference the Observations that support them.

Implementation notes

  • Traceability: Use Condition.evidence.detail to maintain a traceable, computable link between diagnostic conclusions and their supporting findings.
  • Symptom clustering: Multiple symptom Observations can be grouped using Observation.hasMember, or captured together via a Questionnaire/QuestionnaireResponse or an Observation panel.
  • Temporal context: Add effective[x] elements to Observations and Conditions to correctly reflect timing and sequence.
  • Provenance & certainty: Capture the provenance (who documented the symptom) and the certainty/verification status of the Condition (e.g. Condition.verificationStatus) to clarify whether a diagnosis is provisional, confirmed or refuted.
  • Terminology alignment: Prefer SNOMED CT for clinical concepts (symptoms and conditions) to enable semantic linking. Use LOINC for structured instruments or patient-reported measurements where appropriate. Use ICD-10/ICD-11 for billing/classification purposes while clinical codes are retained for interoperability.
  • Multiplicity: A single Observation (symptom) can corroborate several Conditions; likewise, a single Condition can be supported by several Observations.

Summary

Aspect Symptom Diagnosis
Clinical nature Experienced or observed manifestation Underlying cause or interpretation
Primary FHIR resource Observation Condition
Relationship element Observation.extension:associatedSymptomOrCondition Condition.evidence.detail
Typical codes SNOMED CT (e.g. chest pain), LOINC (e.g. nausea severity) SNOMED CT, ICD-10 (e.g. pneumonia, migraine)
Example relationship A symptom supports one or more Conditions A Condition references several supporting Observations

Best practice

Use Condition.evidence.detail to link Conditions to the Observations (symptoms) that support them. Optionally, use Observation.extension:associatedSymptomOrCondition to state the reverse relationship. Ensure consistent coding, provenance and temporal alignment to support computable reasoning and interoperability.