Avoidability of adverse drug reactions spontaneously reported to a French regional drug monitoring centre.

Background: Adverse drug reactions (ADRs) are now recognized as a major category of iatrogenic illness in terms of morbidity and mortality.

Objective: To describe the type and frequency of avoidable ADRs spontaneously reported to a regional drug monitoring centre following inappropriate prescribing, as a basis for preventive actions.

Methods: A prospective, observational study of ADRs reported to the Regional Drug Monitoring Centre of Tours, France, between 26 November 2002 and 28 November 2003. The outcome measure was ADRs secondary to inappropriate prescribing that were defined as entirely or partly avoidable, i.e. at least one of the recommendations in various sections of the summary of product characteristics (SPC; indication, route of administration, dose, duration of treatment, dose adaptation, precautions for use, monitoring of treatment, absolute contraindications and contraindicated interactions) had not been respected. The link between the lack of conformity of the drug prescription with the SPC and occurrence of the ADR was evaluated by a working group using two criteria: (i) is nonconformity of the prescription of this drug a known and validated risk factor for this ADR?; and (ii) are there other aetiologies or other risk factors for this ADR?

Results: Three hundred and sixty ADRs in 294 adults and 66 children were analysed. The prescription was considered inappropriate for 213 of the 659 (32%) drugs implicated in ADRs, corresponding to 161 patients (45%). The ADR was adjudged entirely avoidable for 32 (9%) patients, partly avoidable for 28 (8%) patients and unavoidable for 300 (83%) patients. Not taking into account a history of allergy or altered renal function and not respecting the recommended dose were the most frequent causes of entirely avoidable ADRs. Allopurinol and lamotrigine were the drugs most frequently involved in serious avoidable ADRs.

Conclusions: Preventive actions should focus on more systematic allergy checks when prescribing drugs and on dose adaptation in cases of altered renal function.