Basic Principles

BASIC PRINCIPLES

The basic principles are as follows:

·        The causality is judged only on the data present in the case, in abstraction of all published data concerning the drug-reaction association. Each case is judged on its own merits (intrinsic imputability) to ensure maximal identification of possible new reactions. This also ensures time-independent classification. Previous publications and labelling, which vary over time, are only indicated, and are not an integral part of the imputability.

·    The causality is assessed on each drug-reaction pair presented by the patient at the time of the event, or that could be involved (such as previously stopped medication that could result in unidentified withdrawal symptoms).

This method is thus very dependent on the Regional Centre/drug information centre system, where there is early interaction with the reporter, so that informa-tion can be accrued in real-time, rather than having to judge a case a posteriori on incomplete information, as is usually the case in most paper-based spontaneous reporting systems where the reporter has already made up his mind on causality when reporting, and infor-mation is only present on the drug suspected by the reporter who often has no formal pharmacological or ADR-assessment training.

The method relies on a set of criteria that are, in fact, common to all causality assessment methods, so that it is easy to reapply other causality meth-ods if the proper information has been obtained. It is perforce very general in its definition of criteria, and much attention has been devoted to refining defini-tions of these criteria for specific reactions, and even for specific drug-reaction associations (Habibi et al., 1988; Fournier et al., 1989; Roujeau et al., 1989; Vigeral et al., 1989; Benichou, 1990; Benichou and Solal-Celigny, 1991).

There are six main criteria, three for chronology (time sequence) and three for semiology (signs and symptoms). These are described below.