Coding, Dictionaries & Establishing PV Programs
To detect global safety signals, the world must speak a single, standardized medical language. This unit introduces the massive coding dictionaries (like MedDRA and ATC) used to translate chaotic doctor’s notes into standardized global databases. Furthermore, it outlines the practical, logistical frameworks required to physically establish a functioning Pharmacovigilance department within a local hospital, a multinational pharmaceutical industry, or a Contract Research Organization (CRO).
Syllabus & Topics
- 1Drug and Disease Classification: ATC System (Anatomical Therapeutic Chemical): A global classification system by the WHO. It strictly classifies drugs at 5 different levels according to the organ/system they act on, and their therapeutic, pharmacological, and chemical properties. Daily Defined Doses (DDD): The assumed average maintenance dose per day for a drug used for its main indication in adults (used for global drug utilization statistics). INN (International Nonproprietary Names): The globally recognized, official generic name for a drug substance (e.g., ‘Paracetamol’, universally preventing brand-name confusion).
- 2Drug Dictionaries & Coding in PV: The Problem: One doctor writes ‘Heart attack’, another writes ‘Myocardial infarction’, another translates it into Spanish. Computers cannot analyze this raw data. Medical Coding solves this by translating text into standardized numerical codes. WHO-ART (Adverse Reaction Terminologies): An older dictionary developed by the WHO. MedDRA (Medical Dictionary for Regulatory Activities): Created by the ICH. The absolute global gold standard. Highly structured hierarchy consisting of 5 levels: SOC (System Organ Class) → HLGT (High Level Group Term) → HLT (High Level Term) → PT (Preferred Term) → LLT (Lowest Level Term). Eudravigilance Medicinal Product Dictionary (XEVMPD): Used strictly within the European Union.
- 3Standardised MedDRA Queries (SMQs): Pre-defined lists of MedDRA terms grouped together that all relate to a defined medical condition (e.g., ‘Severe Cutaneous Adverse Reactions’). SMQs allow computer databases to instantly sweep through millions of reports and extract all possible cases related to a specific terrifying toxicity.
- 4Information Resources in Pharmacovigilance: Basic Drug Information Resources: Standard pharmacology textbooks, the British National Formulary (BNF), Martindale (The Complete Drug Reference). Specialized Resources for ADRs: Meyler’s Side Effects of Drugs (the definitive global encyclopedia of adverse reactions), Toxnet, Micromedex, and databases like VigiAccess (public interface for VigiBase).
- 5Establishing a PV Programme (Hospital & Industry): In a Hospital: Requires forming a Pharmacy and Therapeutics (P&T) committee, developing accessible ADR reporting forms (Yellow Cards), dropping them in wards, and training nurses and doctors to overcome ‘reporting apathy’. In Industry: A heavily legislated department headed by a QPPV (Qualified Person for Pharmacovigilance). Responsible for collecting global data, maintaining the safety database, writing massive aggregate safety reports (PSURs), and signaling regulatory agencies.
- 6Contract Research Organisations (CROs) & National Programmes: CROs: Massive outsourcing companies (like IQVIA or Parexel) hired by pharma companies to handle their overwhelming PV data processing, MedDRA coding, and report writing. National Programme: Establishing a central government node (like PvPI in India) to aggregate data from all peripheral regional hospitals, analyzing it to formulate national regulatory action (like banning a drug in India).
Learning Objectives
Exam Prep Questions
Q1. Why do we use “MedDRA” instead of letting doctors type whatever they want?
Computers analyze data using exact matches, but doctors around the world may describe the same medical problem in many different ways. For example, one doctor may write “stomach ache,” another “gastric spasm,” and another use a different language altogether. To a computer database, these appear as completely different events.
MedDRA (Medical Dictionary for Regulatory Activities) solves this problem by converting all these descriptions into a standardized medical term and code (for example, the Preferred Term “Abdominal Pain”). This standardization allows global pharmacovigilance databases to accurately detect safety signals and identify whether a drug is causing increased reports of a particular adverse effect.
Q2. What is the purpose of “Daily Defined Dose” (DDD)?
The Daily Defined Dose (DDD) is a statistical unit created by the World Health Organization (WHO) to measure drug consumption at a population level. It represents the assumed average maintenance dose per day for a drug used for its main indication in adults.
DDD is not used for prescribing patients. Instead, it allows researchers and policymakers to compare drug usage across different countries or healthcare systems, even when drugs are sold in different strengths, package sizes, or prices. This makes it easier to analyze patterns such as antibiotic consumption between nations.
Q3. Why do doctors in hospitals often fail to report Adverse Drug Reactions (ADRs)?
Failure to report ADRs is a widespread problem known as underreporting. Several factors contribute to this issue:
Time constraints: Busy hospital environments leave little time to complete reporting forms.
Uncertainty: Doctors may not be completely sure that the drug caused the reaction.
Fear of legal consequences: Some clinicians worry that reporting ADRs could imply medical negligence.
Lack of awareness or access: Reporting systems or forms may not be easily available.
Hospital pharmacovigilance programs aim to educate healthcare professionals, simplify reporting systems, and encourage a culture of safety reporting to overcome these barriers.