TheMedDRA (Medical Dictionary for Regulatory Activities)is a standardized medical terminology used for coding and analyzing adverse event (AE) and medical history data in clinical trials. Its hierarchical structure supports aggregation, analysis, and reporting across varying levels of medical specificity.

Frommost specific to least specific, the hierarchy is as follows:

Lowest Level Term (LLT):The most granular term, often reflecting the verbatim text reported by the investigator.

Preferred Term (PT):The standardized medical concept representing one or more LLTs describing the same condition.

High Level Term (HLT):A grouping of related PTs describing similar medical conditions.

High Level Group Term (HLGT):A broader grouping of related HLTs.

System Organ Class (SOC):The highest level of classification, grouping HLGTs by body system or etiology (e.g., cardiac disorders, infections).

Thus, the correct order — frommost specific to least specific— is:

LLT → PT → HLT → HLGT → SOC, which corresponds tooption D.

Reference (CCDM-Verified Sources):

SCDM GCDMP, Chapter: Medical Coding and Dictionaries, Section 5.2 – MedDRA Hierarchical Structure

ICH M1 MedDRA Terminology Guide, Version 26.0 – Hierarchy Overview

ICH E2B(R3) Guidelines – Clinical Safety Data Management