MII IG PRO, published by Medizininformatik-Initiative. This guide is not an authorized publication; it is the continuous build for version 2026.2.0 built by the FHIR (HL7® FHIR® Standard) CI Build. This version is based on the current content of https://github.com/medizininformatik-initiative/kerndatensatzmodul-proms/ and changes regularly. See the Directory of published versions

ID Systematics

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A consistent identifier system is essential for the standardized representation of PRO data in the MII context.

Important distinction: Identifiers are explicitly intended as MII-internal business identifiers and should not be confused with semantic codes (LOINC, SNOMED CT) of questionnaires and questionnaire items, which serve terminological annotation in open standards.

Scope of Identifier Usage

Identifiers are needed in the following contexts:

1. Questionnaire Identification: Unique designation of individual questionnaires (e.g., PHQ-9, EQ-5D-5L)
2. Question Group Identification: Designation of item blocks/domains (e.g., PROMIS-29 Physical Function 4a)
3. Item Identification: Unique designation of individual questions (e.g., EQ-5D-5L Mobility)
4. Answer Option Identification: Designation of specific answer choices (e.g., "0: No pain")
5. Score Identification: Unique designation of score definitions (e.g., EQ-5D-VAS-Score)
6. Domain Identification: Designation of health-related domains (e.g., Depression, Anxiety)

FHIR Resource and File Naming Conventions

The MII PRO module follows the established MII naming scheme:

Basic Structure

mii-[type]-[module]-[specification]

• [type]: FHIR resource type (see table below)
• [module]: pro (Patient-Reported Outcomes)
• [specification]: Detailed description of the artifact

Resource Type Abbreviations

General MII Conventions

These abbreviations are used MII-wide across all modules:

PRO Module-Specific Additions

These abbreviations have been developed specifically for the PRO module:

Note on QuestionnaireResponse: The introduction of a qr abbreviation for QuestionnaireResponse was discussed. After thorough review, it was decided that QuestionnaireResponses should be classified as either:

• Definitional profiles under pr (e.g., mii-pr-pro-questionnaire-response) or
• Concrete examples under exa (e.g., mii-exa-pro-phq-9-response)

depending on their intended purpose.

Important: File names and resource IDs are identical and consistently use lowercase with hyphens.

Namespace System for Questionnaires

Fundamental Principles

• Human readability: Use of descriptive, understandable names instead of hashed strings
• Consistency: Uniform spelling and structure within the namespace
• Uniqueness: Clear differentiation of various instruments and versions

Namespace Structure for Questionnaires

mii-qst-pro-[organization]-[instrument]-[variant]

Challenges in Namespace Definition

Problem: PROM instrument abbreviations are not unique and may have identical names in different specialties.

Complexity factors:

1. Multiple instruments of one organization (e.g., various PROMIS questionnaires)
2. Different major versions of a questionnaire (e.g., BDI vs. BDI-II)
3. Parent-proxy versions for parent/child assessments
4. Age-appropriate variants in pediatrics
5. Language variants with content differences between languages

Important note: These different questionnaires may produce identical or comparable scores, which must be considered in score assignment.

Established Namespaces (Current Status)

Structured by organization:

# EuroQol Organization
mii-qst-pro-euroqol-eq5d5l     # EQ-5D-5L (Five Level)
mii-qst-pro-euroqol-eq5dy5l    # EQ-5D-Y-5L (Youth Version)
mii-qst-pro-euroqol-eq5d3l     # EQ-5D-3L (Three Level)

# PROMIS Organization
mii-qst-pro-promis-promis29         # PROMIS-29 Profile v2.1
mii-qst-pro-promis-depression-sf4a  # PROMIS Depression Short Form 4a

# PHQ Family (Pfizer/Spitzer)
mii-qst-pro-phq-phq9          # Patient Health Questionnaire-9
mii-qst-pro-phq-gad7          # Generalized Anxiety Disorder-7
mii-qst-pro-phq-phqsads       # PHQ-SADS

# Beck Inventories
mii-qst-pro-beck-bdi2         # Beck Depression Inventory-II

Note: The namespace system is continuously expanded and refined based on the requirements of new instruments.

LinkId Conventions for Questionnaire Items

Basic Structure for linkIds

[instrument-prefix]-[item-type]-[identifier]

Currently Implemented Patterns

1. Question Abbreviation + Numbering (with Leading Zeros)

Pattern: {instrument}-q{number} (number always two digits with leading zero)

# PHQ-9 Examples
phq-phq9-q01        # Item 1: "Little interest or pleasure in doing things"
phq-phq9-q02        # Item 2: Feeling down
phq-phq9-q09        # Item 9: Suicidal ideation
phq-phq9-score-total # Total score

# BDI-II Examples
bdi-bdi2-q01        # Item 1: Sadness
bdi-bdi2-q02        # Item 2: Pessimism
bdi-bdi2-q21        # Item 21: Loss of interest in sex
bdi-bdi2-score-total # Total score

2. EuroQol Domain-Based IDs

Pattern: {instrument}-q{number}-{domain-code} (number two digits)

# EQ-5D-5L Examples
euroqol-eq5d5l-q01-MO    # Mobility
euroqol-eq5d5l-q02-SC    # Self-Care
euroqol-eq5d5l-q03-UA    # Usual Activities
euroqol-eq5d5l-q04-PD    # Pain/Discomfort
euroqol-eq5d5l-q05-AD    # Anxiety/Depression
euroqol-eq5d5l-vas       # Visual Analog Scale

3. PROMIS Item Bank IDs

Pattern: {instrument}-{item-bank-id} (based on official PROMIS codes)

# PROMIS Depression SF 4a
promis-eddep04           # PROMIS Item EDDEP04
promis-eddep06           # PROMIS Item EDDEP06
promis-eddep29           # PROMIS Item EDDEP29
promis-eddep05           # PROMIS Item EDDEP05

# PROMIS-29 Physical Function Items
promis-pfa11             # Physical Function Item (based on validation study)
promis-pfa21             # Physical Function Item
promis-pfa23             # Physical Function Item
promis-pfa53             # Physical Function Item

Score Item Conventions

Pattern: {instrument}-{score-type}-{variant}

# Different score types
{instrument}-score-raw          # Raw score
{instrument}-score-tscore       # T-Score (PROMIS)
{instrument}-score-total        # Total score
{instrument}-score-index        # Index score (EQ-5D)
{instrument}-score-vas          # VAS score
{instrument}-score-profile      # Profile score

Special Item Types

Display Items (Instructions, Descriptions)

{instrument}.Description        # Main description/instruction
{instrument}.{section}          # Section-specific description

Examples:

PHQ-9.Description               # PHQ-9 main instruction
PROMIS-Depression.Description   # PROMIS Depression instruction

Decision Matrix for linkId Patterns

Consistency Rules

1. Lowercase: All linkIds consistently use lowercase
2. Hyphens: Components separated by hyphens (no underscores)
3. Prefix consistency: Same instrument prefix for all items of a questionnaire
4. Leading zeros: Numbering always two digits (q01, q02, …, q10, q11, …)
5. Uniqueness: LinkIds must be unique within a questionnaire
6. Human readability: IDs should be understandable for developers and clinicians

Handling International Standards

LOINC Integration: Where available, LOINC is used as the code element, while linkId follows the MII internal system:

//FSH
* item[1].linkId = "phq-phq9-q01"           # MII internal ID
* item[1].code = $LNC#44250-9               # LOINC code for semantic annotation

PROMIS Integration: Official PROMIS item IDs are adopted as linkId where available:

//FSH
* item[1].linkId = "promis-eddep04"         # Official PROMIS item code
* item[1].code = $LNC#71969-0               # LOINC code (if available)

Challenges and Solutions

Problem: Multiple Use of Items

Situation: PROMIS items can appear in different questionnaires (e.g., EDDEP04 in PROMIS-29 and PROMIS Depression SF 4a)

Solution: Consistent use of the same linkId across all questionnaires enables:

• Simplified FHIRPath expressions for cross-domain calculations
• Reusability of validation logic
• Consistent data evaluation

Problem: Missing Official Item IDs

Situation: Not all instruments have standardized item codes

Solution: Fallback to structured numbering with semantic additions:

{instrument}-q{NN}              # Base pattern (leading zero!)
{instrument}-q{NN}-{domain}     # With domain information

Best Practices for New Instruments

1. Check for official item IDs: Use established codes (PROMIS, LOINC) where available
2. Consistent prefixes: Follow existing namespace conventions
3. Leading zeros: Always use two-digit numbering (q01-q99)
4. Domain codes: Add domain abbreviations for structured instruments
5. Score suffix: Use clear score designations (-score-total, -score-raw, etc.)

Terminology Strategies for Answer Options

Strategic Decision: answerOption vs answerValueSet

The choice between inline answerOption and external answerValueSet definitions is a fundamental architectural decision that significantly impacts maintainability, reusability, and interoperability.

Decision Matrix

Implementation Examples

Pattern 1: LOINC + itemWeight Extensions (PHQ-9)

//FSH
* item[=].answerOption[0].valueCoding.system = $LNC
* item[=].answerOption[0].valueCoding.code = #LA6568-5
* item[=].answerOption[0].valueCoding.display = "Not at all"
* item[=].answerOption[0].extension.url = "http://hl7.org/fhir/StructureDefinition/itemWeight"
* item[=].answerOption[0].extension.valueDecimal = 0

Pattern 2: MII CodeSystem + ValueSet (BDI-II)

//FSH
// Questionnaire
* item[=].answerValueSet = "http://www.medizininformatik-initiative.de/fhir/ext/modul-pro/ValueSet/mii-vs-pro-bdi-bdi2-short"

// CodeSystem
* #bdi-bdi2-answer-1 ^property[+].code = #bdi-bdi2-itemWeight
* #bdi-bdi2-answer-1 ^property[=].valueDecimal = 1

Pattern 3: Simple Inline Codes (EQ-5D-5L)

//FSH
* item[=].answerOption[0].valueCoding.display = "I have no problems in walking about"
* item[=].answerOption[0].valueCoding.code = #1

Decision Guide

First check the Questionnaire Capabilities:

Use answerValueSet + MII CodeSystem when:

• displayable = false, calculatable = true (like BDI-II)
• Optimization for pure score calculation without display overhead
• Background calculations without user interaction

Use inline answerOption when:

• displayable = true (interactive forms)
• LOINC codes with score weights are available
• Simple, static answer lists (5 or fewer options)
• Rich metadata per option (translations, weights)

Additional answerValueSet + MII CodeSystem criteria:

• Multiple answer format variants needed (short/long)
• Reuse across multiple questionnaires planned
• Complex scoring requirements with variable weights
• German healthcare system specifics required

Detailed documentation: Terminology Strategies