Inherent Limitations of the Yellow Card System for the Detection of Unsuspected Adverse Drug Reactions

Abstract

<jats:p> The number of cases of an adverse reaction which could be seen by individual doctors was investigated taking realistic values for the frequency of drug prescribing and a range of frequencies of adverse drug reactions. The results indicated that, for almost all drugs, general practitioners (GPs) will seldom see other than single cases of an adverse reaction. It is argued that doctors will be unlikely to recognize an adverse reaction from a single case (unless it presented with some striking clinical features) so that potential new adverse reactions will rarely be reported by GPs under the Yellow Card scheme. A similar analysis for hospital doctors indicated that clinicians working in some specialities, may have a greater chance of seeing more than one case of an adverse reaction. A review of the identification of several important adverse reactions revealed that all the reports from British doctors were submitted by clinicians with hospital appointments. This study suggests that the major part of the operation of the Yellow Card system will contribute little to the identification of adverse reactions and that its organization and activities need to be reassessed. A modified system designed to encourage reporting by hospital clinicians could be of greater value. </jats:p>

Reported paediatric adverse drug reactions in the UK 2000–2009

“…These data are derived entirely from the UK spontaneous ADR reporting scheme (MHRA Yellow Card Scheme), and are subject to the limitations of any such scheme. These include under‐reporting of ADRs (secondary to lack of recognition or failure to carry out the reporting process) [27, 28], inability to calculate the true incidence of any ADRs reported [29, 30], variable quality in Yellow Card completion [29], assessment of causality between a drug and an ADR and difficulty in identifying ADRs with long latency periods following use of the drug [31]. Under‐reporting in particular is believed to be very common, with some estimates that up to 95% of all ADRs are not reported [10, 11].…”

Antiepileptic drugs and pregnancy outcomes

“…The strongest data indicate that valproate exposure is associated with a 1-2% risk of neural tube defects (NTDs), a 10- to 20-fold increase over the general population (EURAP), an increased risk of neurodevelopmental deficits, reduced verbal abilities, and poorer attentional tasks [Bromley et al 2009; Kantola-Sorza et al, 2007; McVearry et al, 2009; Meador et al, 2008, 2011; Nadebaum, 2011; Thomas et al, 2008]. The astute clinician has always been credited with being the primary means of identifying potential human teratogens [Crombie, 1984; Carey et al, 2009], and this has been the case for AEDs as well.…”

Teratogenic effects of antiepileptic drugs

“…The astute clinician has always been credited with being the primary means of identifying potential human teratogens [8,9], and this has been the case for AEDs as well. Now that the teratogenicity of these compounds has been established for over 40 years, refining risk assessments depends on the quality of the epidemiological data that can be acquired.…”