Table 2 Criteria used for assessing causality of suspected medication-related problems (based on Howard et al18)
1Known adverse drug reaction, toxic reaction, response to omission of therapy or inadequate therapy
2Reasonable temporal relationship between commencement or cessation/omission of therapy and onset of problem
3Risk of further problems likely to be reduced by dose reduction or increase, discontinuation, closer monitoring or commencement of therapy
4Not explained by any other known condition of predisposition to the patient, or This condition/predisposition is likely to be exacerbated by the presence/absence of the drug
5For drug toxicity:
    Symptoms reappeared upon re-exposure
    Laboratory tests showed toxic drug levels or drug-induced metabolic disturbances that explained the symptom
    Symptoms resolved on dose reduction or discontinuation of the drug
For drug omission:
    Symptoms resolved upon re-introduction of the drug or dose increase
  • If five criteria fulfilled, then definite. If four criteria fulfilled, then probable. If three criteria fulfilled, then possible. If two or fewer criteria fulfilled, then either not drug-related or unevaluable.