Table 3 WHO-UMC causality categories
Causality term | Assessment criteria |
|---|---|
Certain | • Event or laboratory test abnormality, with plausible time relationship to drug intake • Cannot be explained by disease or other drugs • Response to withdrawal plausible (pharmacologically, pathologically) • Event definitive pharmacologically or phenomenologically (i.e., an objective and specific medical disorder or a recognized pharmacological phenomenon) • Rechallenge satisfactory, if necessary |
Probable/likely | • Event or laboratory test abnormality, with reasonable time relationship to drug intake • Unlikely to be attributed to disease or other drugs • Response to withdrawal clinically reasonable • Rechallenge not required |
Possible | • Event or laboratory test abnormality, with reasonable time relationship to drug intake • Could also be explained by disease or other drugs • Information on drug withdrawal may be lacking or unclear |
Unlikely | • Event or laboratory test abnormality, with time to drug intake • that makes a relationship improbable (but not impossible) • Disease or other drugs provide plausible explanations |