Pharmacovigilance Reference
MedDRA Lookup Guide: SOC, HLGT, HLT, PT, and LLT Hierarchy
A public, non-licensed MedDRA hierarchy reference for PV teams learning how adverse event coding supports ICSRs, aggregate reporting, and signal detection.
Quick Answer
MedDRA is the global standard terminology for coding adverse events in pharmacovigilance. The hierarchy runs from System Organ Class (SOC) down through HLGT, HLT, Preferred Term (PT), to Lowest Level Term (LLT). Case processors code reporter verbatim text to an LLT, which maps to one PT for analysis and SOC tabulation. Standardised MedDRA Queries (SMQs) group PTs for signal topics. This page is an educational reference—it does not provide licensed MedDRA codes or official term lookup.
Interactive Reference
Search Public MedDRA Concepts
Showing 8 of 8 concepts
System Organ Class
The broadest MedDRA grouping, commonly aligned to body systems, etiologies, or purpose-built medical groupings.
SOC groupings help aggregate coded events for safety summaries, periodic reports, and signal review dashboards.
A PT may appear under more than one SOC, but one SOC is designated as primary for tabulation.
High Level Group Term
A high-level grouping that collects related HLTs beneath a SOC.
HLGTs support mid-level review when individual PTs are too granular but SOCs are too broad.
HLGT labels and memberships are official MedDRA content and require licensed access for production coding.
High Level Term
A grouping of related PTs within a higher-level clinical concept.
HLTs help reviewers scan medically related PTs during case series review and aggregate analysis.
Use the current licensed MedDRA browser or organization-approved coding tool for exact HLT relationships.
Preferred Term
The distinct medical concept used most often for analysis, case line listings, and signal detection outputs.
ICSR narratives are typically coded from reported verbatim text to an LLT that rolls up to a PT for analysis.
This page does not provide official PT names, numeric codes, or current version membership.
Lowest Level Term
The most granular level used to capture reported wording, synonyms, lexical variants, and near-synonyms.
Case processors often code verbatim adverse event text to the closest appropriate LLT, which maps to a single PT.
Exact LLT selection must follow licensed MedDRA content, coding conventions, and local SOPs.
Standardised MedDRA Query
A validated grouping of MedDRA terms designed to retrieve cases for a defined medical condition or safety topic.
SMQs support signal detection, special topic surveillance, and medical review across multiple related PTs.
SMQ term lists, algorithms, and narrow/broad scopes are official MedDRA content.
Primary System Organ Class
The SOC assignment used for standard tabulations when a PT is linked to multiple SOCs.
Primary SOC assignment helps avoid double counting in standard aggregate tables while retaining multiaxial relationships.
Primary SOC assignment is part of official MedDRA structure and should be checked in the licensed release.
Multiaxial relationships
The ability for a PT to be represented in more than one SOC where medically appropriate.
Multiaxiality improves retrieval across relevant medical perspectives, but analysts must understand primary SOC tabulation.
Production analysis should document the MedDRA version, query scope, and SOC handling rules.
Hierarchy
How the MedDRA Hierarchy Works
MedDRA organizes medical concepts from broad groupings to granular reported wording. In a typical PV workflow, the coder captures the reporter's verbatim adverse event wording, selects the closest appropriate LLT in a licensed MedDRA tool, and analyzes the resulting PT in case listings, aggregate tables, and signal detection outputs.
SOC
System Organ Class
Broad medical grouping used for high-level tabulation.
HLGT
High Level Group Term
Groups related HLTs under a broader clinical area.
HLT
High Level Term
Groups medically related PT concepts.
PT
Preferred Term
Main analytical concept used in listings and signal detection.
LLT
Lowest Level Term
Granular coding level for reported wording and variants.
Non-Licensed Hierarchy Demo
Example only: a reporter phrase such as "felt dizzy after the first dose" would be reviewed against licensed MedDRA LLTs. The chosen LLT would roll up to one PT, which then supports SOC-level tabulation. This page intentionally avoids listing official MedDRA terms or codes.
Coding Workflow
Where LLT, PT, and SOC Fit in Case Processing
Capture the verbatim report
Start from the reporter wording in the ICSR, not from an assumed diagnosis. Preserve clinical context for medical review.
Select the closest LLT in a licensed tool
A trained coder chooses the most appropriate LLT using the current licensed MedDRA release, coding conventions, and local SOPs.
Review the PT roll-up
The selected LLT maps to a PT, which becomes the common analysis level for listings, aggregate reports, and signal detection.
Check SOC and query context
Analysts review the primary SOC, possible multiaxial SOC relationships, and relevant SMQs when building safety summaries.
Document version and rationale
Record the MedDRA version, coding decision, query scope, and any medical review rationale for auditability.
The practical point for reviewers is that coding precision affects downstream evidence. If a verbatim is coded too broadly, similar cases may scatter across analysis outputs. If it is coded too narrowly or inconsistently, case retrieval, SMQ review, and disproportionality screening can become noisy.
SMQs
How SMQs Support Signal Detection
Standardised MedDRA Queries help safety teams retrieve groups of medically related events for a defined safety topic. A signal reviewer may use a narrow scope to focus on more specific cases, or a broader scope to avoid missing clinically relevant reports during exploration.
SMQs are especially useful when a potential risk can be reported using many related PTs. They do not replace medical judgment, case narrative review, or documented signal validation.
ICSRs and Signals
Why MedDRA Matters in ICSRs and Signal Detection
MedDRA gives sponsors, CROs, regulators, and database operators a common medical language for adverse event exchange. In ICSR processing, coded terms help transform unstructured reporter descriptions into standardized data fields suitable for E2B transmission, case retrieval, and medical review.
In signal detection, PT-level consistency directly affects case counts, disproportionality measures, trend review, and case series construction. Analysts should always preserve the MedDRA version and query assumptions used for an output.
FAQ
MedDRA Lookup Guide FAQ
Does this page provide official MedDRA term lookup or codes?
No. This page is a public educational reference about MedDRA hierarchy, coding workflow, SMQs, primary SOC, and multiaxiality. It does not provide licensed MedDRA term lists, numeric codes, or production coding output. Official MedDRA content requires appropriate MSSO subscription or licensing.
What is the MedDRA hierarchy?
MedDRA is organized from broad to granular levels: SOC, HLGT, HLT, PT, and LLT. In common PV workflows, reported wording is coded at the LLT level and then rolls up to a PT for analysis and to SOC groupings for tabulation.
How does an LLT map to a PT and SOC?
An LLT maps to one PT. The PT then sits within the MedDRA hierarchy and has a primary SOC for standard tabulation. Some PTs have multiaxial links to additional SOCs where medically relevant.
What are SMQs used for in pharmacovigilance?
Standardised MedDRA Queries are curated groupings used to retrieve sets of medically related cases for safety topics. They can support signal detection, case series review, and aggregate safety analysis, but the official SMQ content requires licensed MedDRA access.
Why does MedDRA matter for ICSRs and signal detection?
MedDRA standardizes adverse event terminology across regions, products, and databases. Consistent coding improves ICSR exchange, aggregate reporting, case retrieval, disproportionality analysis, and medical review of potential safety signals.
What is primary SOC allocation?
When a PT appears under more than one SOC, primary SOC is the assignment used for standard one-place tabulation in aggregate reports. Multiaxial links allow retrieval from additional SOC perspectives. Both are pre-defined in licensed MedDRA releases—not chosen ad hoc at coding.
What is multiaxiality in MedDRA?
Multiaxiality allows a PT to appear in more than one SOC when medically appropriate—for example, grouping by etiology and manifestation. Analysts must understand primary SOC rules to avoid double counting in standard tables while still using multiaxial retrieval when clinically relevant.
How does MedDRA differ from WHO-ART?
WHO-ART was an earlier WHO adverse reaction terminology largely superseded by MedDRA in ICH regions. Current ICSR transmission under ICH E2B(R3) expects MedDRA for reaction terms in most regulatory exchanges. Historical WHO-ART-coded data may require mapping strategies during database migrations.
Where do coders select the correct LLT?
Production coding uses the licensed MedDRA Web-Based Browser, Desktop Browser, or organization-approved safety database coding tools—not public web summaries. Coders follow MedDRA Term Selection: Points to Consider (MTS:PTC) and local SOPs, selecting current LLTs that reflect verbatim reporter wording.
Why must MedDRA version be documented in safety analysis?
Term membership, LLT–PT links, and SMQ content change between MedDRA versions. Signal detection, PSUR/PBRER tables, and E2B submissions must record the version used so results are reproducible and comparable across reporting cycles.
What training does MSSO provide for MedDRA coding?
The MedDRA Maintenance and Support Services Organization (MSSO) offers free webinars, face-to-face courses, introductory guides, and coding basics materials for subscribers. Topics include hierarchy, SMQs, primary SOC rules, and term selection conventions—complementing this public educational overview.
How does MedDRA coding connect to other PV tools on this site?
After coding at LLT/PT level, cases flow through seriousness triage, causality assessment, ICSR processing, aggregate reporting, and disproportionality screening. Use the Seriousness Checker, Case Processing Guide, Signal Detection Calculator, and Aggregate Reporting Calendar alongside licensed MedDRA browsers for end-to-end PV workflows.
Sources
Public Documentation Used for This Reference
- MedDRA MSSO: MedDRA Hierarchy
- MedDRA MSSO: Standardised MedDRA Queries
- ICH E2B(R3): Electronic Transmission of ICSRs
- Therapeutic Goods Administration: MedDRA
- Competitive landscape: MedDRA MSSO hierarchy documentation and the licensed Web-Based Browser provide authoritative term lookup for subscribers but require MSSO licensing for production coding. MSSO Coding Basics webinar covers hierarchy and term selection in PDF format without interactive PV hub links. NovaPharmaNews offers a free public educational guide with searchable concept cards, SMQ and multiaxiality context, and integrated links to case processing, signal detection, and seriousness tools—not a replacement for licensed MedDRA browsers.
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