The use of the WHO-UMC system for standardised case causality assessment

Overview

An inherent problem in pharmacovigilance is that most case reports concern suspected adverse drug reactions. Adverse reactions are rarely specific for the drug, diagnostic tests are usually absent and a rechallenge is rarely ethically justified. In practice few adverse reactions are ‘certain’ or ‘unlikely’; most are somewhere in between these extremes, i.e. ‘possible’ or ‘probable’.