Introduction: Pharmacovigilance relies on robust causality assessment methods to determine whether an adverse event is related to a drug. B. Pharm students must understand key frameworks—WHO‑UMC, Naranjo Algorithm, probabilistic approaches, and expert judgment—and core concepts like temporality, dechallenge/rechallenge, dose–response, alternative causes, and biological plausibility. Knowing strengths, limitations, scoring thresholds, documentation and case processing helps in signal detection, safety reporting, and clinical decision-making. Practical case-based exercises, documentation standards, and awareness of inter‑rater variability improve consistency in causality decisions. Regular training and use of algorithms enhance reproducibility and regulatory compliance. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. What is the main purpose of causality assessment in pharmacovigilance?
- To determine the exact biochemical mechanism of the reaction
- To assess the likelihood that a drug caused an adverse event
- To calculate the cost of adverse drug reactions
- To decide marketing strategies for the drug
Correct Answer: To assess the likelihood that a drug caused an adverse event
Q2. Which causality tool uses a structured questionnaire with weighted scores to classify probability?
- WHO-UMC system
- Expert global introspection
- Naranjo Algorithm
- Bayesian network analysis
Correct Answer: Naranjo Algorithm
Q3. Which WHO-UMC causality category indicates the strongest evidence of drug-relatedness?
- Possible
- Unlikely
- Certain
- Conditional/unclassified
Correct Answer: Certain
Q4. In causality assessment, what does a positive dechallenge imply?
- Adverse event worsened after stopping the drug
- Adverse event resolved or improved after stopping the drug
- Re-exposure produced the same effect
- Alternative cause was confirmed
Correct Answer: Adverse event resolved or improved after stopping the drug
Q5. Which of the following is a limitation of the Naranjo scale?
- Provides definitive proof of causation in all cases
- Does not account well for drug interactions and complex comorbidities
- Is the only WHO-recommended method
- Requires genetic testing results
Correct Answer: Does not account well for drug interactions and complex comorbidities
Q6. A rechallenge resulting in recurrence of the event strongly supports which causality category?
- Unlikely
- Possible
- Probable/likely
- Certain
Correct Answer: Certain
Q7. Which element is most critical for establishing temporality in causality assessment?
- Presence of a similar report in literature
- Time relationship between drug exposure and onset of event
- Patient’s socioeconomic status
- Drug price
Correct Answer: Time relationship between drug exposure and onset of event
Q8. Probabilistic methods in causality assessment primarily use which approach?
- Fixed categorical labels without scores
- Qualitative expert opinions only
- Probability estimation often using Bayesian statistics
- Randomized clinical trial data only
Correct Answer: Probability estimation often using Bayesian statistics
Q9. Which of these improves inter-rater reliability in causality assessment?
- Using multiple unstructured expert opinions without guidance
- Standardized algorithms and training
- Decisions based solely on literature abstracts
- Avoiding documentation of rationale
Correct Answer: Standardized algorithms and training
Q10. In the WHO-UMC system, which category is used when information is insufficient or contradictory?
- Probable/likely
- Unassessable/unclassifiable
- Certain
- Possible
Correct Answer: Unassessable/unclassifiable
Q11. Which factor lowers the probability that a drug caused the adverse event?
- Known temporal association
- Positive dechallenge
- Presence of a clear alternative explanation
- Positive rechallenge
Correct Answer: Presence of a clear alternative explanation
Q12. When applying the Naranjo algorithm, which item contributes to the score?
- Whether the event occurred in an animal study only
- Previous conclusive reports on this reaction
- Market share of the drug
- Patient’s religion
Correct Answer: Previous conclusive reports on this reaction
Q13. Which approach is most suitable for rare adverse events where randomized data are unavailable?
- Spontaneous reporting plus causality assessment and pharmacoepidemiology
- Large randomized trials only
- Ignoring the reports due to rarity
- Drug pricing analysis
Correct Answer: Spontaneous reporting plus causality assessment and pharmacoepidemiology
Q14. Biological plausibility in causality assessment refers to:
- Whether the reaction is described in marketing materials
- Whether a mechanism exists linking the drug to the event
- Whether the patient prefers the drug
- Whether insurance will cover treatment
Correct Answer: Whether a mechanism exists linking the drug to the event
Q15. Which statement about dechallenge and rechallenge is correct?
- Dechallenge response is less informative than rechallenge
- Rechallenge is always ethically acceptable
- Dechallenge and rechallenge results can strengthen causal inference
- Neither is used in modern causality assessment
Correct Answer: Dechallenge and rechallenge results can strengthen causal inference
Q16. Which is NOT typically part of a structured causality assessment?
- Temporal relationship evaluation
- Assessment of alternative causes
- Random patient interviews on drug branding
- Review of prior reports and dose-response
Correct Answer: Random patient interviews on drug branding
Q17. How does confounding by indication affect causality assessment?
- Makes it easier to assign causality to the drug
- Biases assessment because underlying disease may cause the event
- Is irrelevant in spontaneous reports
- Is corrected automatically by the Naranjo scale
Correct Answer: Biases assessment because underlying disease may cause the event
Q18. Which documentation practice is essential when recording causality assessment?
- Stating the final category without rationale
- Detailed rationale including evidence for and against causality
- Only recording the suspected drug name
- Using acronyms without definitions
Correct Answer: Detailed rationale including evidence for and against causality
Q19. In signal detection, aggregate causality assessments are used to:
- Evaluate patterns of suspected drug-event associations across reports
- Replace all clinical trials
- Determine drug pricing
- Certify manufacturing quality
Correct Answer: Evaluate patterns of suspected drug-event associations across reports
Q20. Which category in WHO-UMC would be appropriate when a reasonable time relationship exists but alternative causes are possible?
- Unlikely
- Possible
- Certain
- Unassessable
Correct Answer: Possible
Q21. What role do laboratory tests (e.g., drug levels, biomarkers) play in causality assessment?
- They are never helpful
- They can provide supportive objective evidence linking drug exposure to effect
- They replace the need for clinical assessment
- They are only required for over-the-counter drugs
Correct Answer: They can provide supportive objective evidence linking drug exposure to effect
Q22. Which of the following best describes the “probable/likely” category?
- Event has no temporal relationship to drug
- Event has reasonable time relationship, unlikely explained by other causes, and responds to withdrawal
- Event is definitely caused by a manufacturing defect
- Event is poorly documented and unassessable
Correct Answer: Event has reasonable time relationship, unlikely explained by other causes, and responds to withdrawal
Q23. Why is literature review important during causality assessment?
- To find the drug price history
- To identify previous reports, known ADR profiles, and mechanistic evidence
- To replace patient interviews
- To verify patient identity
Correct Answer: To identify previous reports, known ADR profiles, and mechanistic evidence
Q24. Which approach can quantify uncertainty in causality decisions and update probabilities with new data?
- Static categorical labels only
- Bayesian/probabilistic methods
- Ignoring new reports
- Single-expert judgment without documentation
Correct Answer: Bayesian/probabilistic methods
Q25. In a case where a patient is on multiple drugs, which step is crucial for causality assessment?
- Assume the newest drug is always the cause
- Systematic review of all concomitant medications, timing, and plausible interactions
- Ignore drug interactions and focus on disease
- Report only the primary drug and omit others
Correct Answer: Systematic review of all concomitant medications, timing, and plausible interactions
Q26. Which statement about expert judgment methods is true?
- They are completely unbiased and always reproducible
- They rely on clinical expertise and can complement structured tools but may vary between assessors
- They are illegal in regulatory submissions
- They do not consider dechallenge or rechallenge
Correct Answer: They rely on clinical expertise and can complement structured tools but may vary between assessors
Q27. Which metric indicates the strength of association in epidemiological studies supporting causality?
- Number needed to harm (NNH)
- Relative risk or odds ratio
- Drug manufacturing date
- Prescription frequency only
Correct Answer: Relative risk or odds ratio
Q28. Which practice helps minimize bias when multiple assessors perform causality assessments?
- Each assessor uses a different unshared method
- Blinded structured assessment with consensus discussion and documentation
- Allowing assessors to consult only their own notes
- Not training assessors intentionally
Correct Answer: Blinded structured assessment with consensus discussion and documentation
Q29. A temporally plausible adverse event appears days after starting a drug and improves after stopping, but rechallenge was not done. According to most tools this is:
- Unlikely to be related
- Suggestive of possible or probable causality depending on other evidence
- Automatically classified as certain
- Considered manufacturing defect
Correct Answer: Suggestive of possible or probable causality depending on other evidence
Q30. When reporting a suspected ADR to a regulatory database, what should causality assessment include?
- A clear statement of causality category with supporting evidence and rationale
- Only the reporter’s name
- Marketing claims about the drug
- Unverified rumors
Correct Answer: A clear statement of causality category with supporting evidence and rationale
