Question 4 of 6 Intermediate Concept
What evidence is useful in causality assessment?
Short answer
Causality assessment weighs timing, alternative explanations, dechallenge or rechallenge evidence, biological plausibility, dose relationship and previous evidence. No single feature usually proves drug causation.
Why
Suppose liver enzymes rise after starting a new medicine. Establish the sequence of exposure and injury, baseline tests, competing medicines, viral causes and underlying disease. Examine whether markers improve after withdrawal, while recognising spontaneous recovery or other treatments.
A recurrence after re-exposure can strengthen the association but deliberate rechallenge can be unsafe or unethical. Review known class effects, pharmacological mechanism and case quality. Document what evidence supports a suspicion and what remains unresolved, preferably using a consistent assessment approach for comparable cases.
A disproportionality signal or a positive temporal relationship is a reason to investigate, not a causal verdict. Likewise, an incomplete case may still warrant reporting when minimum criteria and jurisdictional requirements are met. Distinguish individual-case clinical assessment from population-level evidence such as epidemiological studies.
Common mistakes
- Treating a positive dechallenge or a high reporting-odds ratio as conclusive proof
The interviewer might ask next
What additional clinical records could change your assessment of a suspected drug-induced liver injury?