Table 2.

WHO-UMC causality categories

Causality term	Assessment criteria	Yes/no
Certain	Event or laboratory test abnormality, with plausible time relationship to drug intake.	Yes
	Cannot be explained by disease or other drugs.	Yes
	Response to withdrawal plausible (pharmacologically, pathologically).	Yes
	Event definitive pharmacologically or phenomenologically (ie, an objective and specific medical disorder or a recognised pharmacological phenomenon).	Yes
	Re-challenge satisfactory, if necessary.	Yes
	Final outcome	Certain

WHO-UMC, WHO—The Uppsala Monitoring Center.