Understanding Underreporting of Adverse Events
A Global Public Health Analysis by WHO & International Pharmacovigilance Networks
Key Fact: The World Health Organization (WHO) estimates that less than 10% of adverse drug reactions (ADRs) are reported through official channels, creating a critical gap in medication safety surveillance.
What Are Adverse Events?
According to WHO and international pharmacovigilance standards:
- Adverse Drug Reaction (ADR): A harmful, unintended reaction to a medication at normal doses
- Adverse Event (AE): Any unfavorable medical occurrence in a patient using a pharmaceutical product, regardless of causality
- Medical Device Incident: Malfunction or adverse outcome associated with medical equipment use
Global Underreporting Crisis
<10% Of serious ADRs are officially reported
150+ Countries in WHO’s International Drug Monitoring Programme
86% Of healthcare professionals cite time constraints as barrier
Primary Causes of Underreporting
Healthcare Professional Factors:
- Uncertainty about causality: Hesitation when drug-event relationship is unclear
- Time constraints: Complex forms and heavy clinical workloads
- Lack of awareness: Not recognizing events as reportable, especially expected reactions
- Perceived insignificance: Belief that known reactions aren’t worth reporting
- Feedback absence: No follow-up on submitted reports diminishes motivation
Systemic Barriers
- Complex, multi-step reporting processes across different authorities
- Insufficient pharmacovigilance training in medical curricula
- Fragmented reporting systems between drugs and medical devices
- Fear of legal liability or professional consequences
WHO’s Role in Addressing Underreporting
The WHO’s International Drug Monitoring Programme, established in 1968, operates as the global framework for pharmacovigilance:
Key WHO Initiatives:
- VigiBase: Global database containing over 30 million ADR reports from 150+ countries
- Capacity Building: Training programs for low- and middle-income countries
- Standardization: Developing international reporting guidelines and terminologies
- Advocacy: Promoting patient reporting and public awareness campaigns
Critical Insight: WHO emphasizes that underreporting is particularly severe in developing nations, where weak healthcare infrastructure combines with limited pharmacovigilance capacity, masking safety signals that could affect vulnerable populations.
Medical Device Underreporting: A Hidden Gap
Medical device incidents face even greater underreporting challenges:
- Healthcare providers often attribute malfunctions to user error rather than device failure
- No standardized global reporting system comparable to drug pharmacovigilance
- Manufacturers may not receive feedback about device performance issues
- Regulatory overlap between health authorities and device regulators creates confusion
Consequences of Underreporting
Delayed Safety signal detection, allowing harmful products to remain on market
Incomplete Risk-benefit assessments, leading to inadequate labeling updates
Missed Patterns in vulnerable populations (children, elderly, pregnant women)
Global Solutions Framework
For Healthcare Providers:
- When in doubt, report: Don’t wait for causality confirmation
- Use simplified systems: Submit via manufacturer portals or national pharmacovigilance centers
- Report promptly: Serious events should be reported within 24-72 hours
- Include complete data: Patient demographics, timelines, concomitant medications
For Healthcare Organizations:
- Implement EHR-based automated detection triggers
- Provide mandatory pharmacovigilance training
- Establish feedback mechanisms showing how reports improve safety
- Integrate reporting into clinical workflow to reduce barriers
For Patients & Caregivers:
National Pharmacovigilance Center
Drug/Manufacturer Safety Portal
WHO Medicines Safety Portal
Conclusion
Underreporting of adverse events remains the critical weakness in global medication safety surveillance. While WHO provides the international framework, success requires a paradigm shift from passive to active, mandatory reporting culture at all levels.
Every unreported adverse event represents a lost opportunity to prevent harm to future patients. Closing this gap requires technological innovation, regulatory harmonization, and most importantly, recognizing that every report contributes to global health security.
Essential Reporting Resources:
- 📊 WHO Programme: www.who.int/medicines/areas/quality_safety
- 🌐 VigiAccess: vigiaccess.org (Public access to WHO database)
- 📱 Find your national center: Through WHO’s member state directory
Professional Note: This page is for educational purposes. Healthcare providers should follow their national regulatory requirements for adverse event reporting.
Last updated: November 2025 | Based on WHO International Drug Monitoring Programme guidelines