In practice, events are treated as signals if they arouse strong suspicion of a hitherto unrecognised adverse reaction. This may be the result of a single case report of high quality with a positive dechallenge and rechallenge ("definite" relationship), regarded as an index case, or a cluster of cases where the relationship that can be established may be of lesser strength. The number of reports and the strength of the relationship may be such that causality can be confirmed with the data on hand (Coulter and Edwards, 1987).
In order to demonstrate the hypothesis-generating activity of the IMMP, signals generated in 11 drugs over the last 10 years were searched from the agenda material and minutes of the MARC (see above) meetings and from publications. For the purposes of this evaluation a signal was recorded as such if the MARC was alerted prior to the date of the second non-IMMP publication. The date that the MARC was alerted to each signal was recorded and this date was compared with the date of the first two publications (if any) found by Medline and AdisBase searches of the international literature (all languages with an English abstract). Medline was searched from 1985 and AdisBase from 1989. Case reports and clinical trials were included in the searches. AdisBase searches included publications from regulatory authorities internationally. Data sheets were not searched. The dates of any IMMP publications were also recorded. Any recommendations of the MARC as a result of considering the signals were noted. Events that are expected as a result of known pharmacological action (e.g. tremor with beta-agonists) were not recorded as signals.
Was this article helpful?