Table 1: Assessment of Link Between Agent and Event*

Definite Probable Possible Conditional
Appropriate temporal sequence Yes Yes Yes Yes
Known reaction to agent Yes Yes Yes No
Improved with dechallenge1 Yes Yes Yes-No No
Relapse on rechallenge2 Yes ? ? ?
Event reasonably explained by clicinal state or other therapies No No Yes No

*Modified from Karch and Lasagna [7].
1The effects of stopping the drug or reducing the dose.
2Relapse of the effects after restarting the drug.