Table 1.

Roussel Uclaf Causality Assessment Method scale

Category	Score	Likelihood (%)	Description
Highly probable	>8	>75	Highly probable, including “highly likely” and “definite.” The evidence for the drug causing the injury is beyond a reasonable doubt, clear, and convincing
Probable	6–8	50–74	The preponderance of the evidence supports the link between the drug and the liver injury
Possible	3–5	25–49	The evidence for the drug causing the injury is equivocal but present
Unlikely	1–3	<25	There is evidence that an etiological factor other than a drug caused the injury
Excluded	<1	0	Causes could be excluded