BMJ  2006;332:335-339 (11 February), doi:10.1136/bmj.38701.399942.63 (published 18 January 2006)

Research

Case reports of suspected adverse drug reactions—systematic literature survey of follow-up

Yoon Kong Loke, senior lecturer in clinical pharmacology1, Deirdre Price, research assistant2, Sheena Derry, research assistant2, Jeffrey K Aronson, reader in clinical pharmacology2

1 School of Medicine, Health Policy, and Practice, University of East Anglia, Norwich NR4 7TJ, 2 Department of Clinical Pharmacology, University of Oxford, Radcliffe Infirmary, Oxford OX2 6HE

Correspondence to: Y Loke y.loke{at}uea.ac.uk

Abstract

Objective To determine whether anecdotal reports of suspected adverse drug reactions are valuable early warning signals.

Design Systematic literature survey

Data sources We evaluated all case reports of adverse drug reactions published in 1997 in five medical journals. Reports were excluded if the adverse reaction had previously been described in earlier publications and was already listed in the product information of the drug reference source (the British National Formulary (BNF) or the Medicines Compendium). We used the Web of Knowledge Citation Index and Medline for 2003 to identify follow-up studies.

Main outcome measures Primary: the number of suspected adverse reactions subjected to formal validation studies and the findings of these studies. Secondary: the number of instances in which the warning from the case report was incorporated into the product information.

Results We evaluated 63 suspected adverse reactions and found that most (52/63, 83%) had not yet been subjected to further detailed evaluation. Data from controlled studies that supported the postulated link between the drug and the adverse event were available in only three cases. Of the 48 agents listed in the drug reference sources, details of the suspected reaction were subsequently added to the Medicines Compendium in 15 instances, and to the BNF in seven instances. In each case, only one reaction had been confirmed.

Conclusions Published case reports of suspected adverse reactions are of limited value as suspicions are seldom subjected to confirmatory investigation. Furthermore, these alerts are not incorporated into drug reference sources in a systematic manner.


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Rapid Responses:

Read all Rapid Responses

Case reports too quickly dismissed
Jan P Vandenbroucke
bmj.com, 29 Jan 2006 [Full text]
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Even a ‘Lesson of the week’ in the BMJ did NOT make much of a difference
George I. Varughese MRCPI; MRCP(U.K.), et al.
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Case reports vital for pharmacovigilance
Douglas E. Ball
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Not always so quick
Christopher Anton
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The importance of anecdotal case reports should not be underestimated
Martin H Goldman
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Case reports of suspected adverse drug reactions
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bmj.com, 20 Feb 2006 [Full text]
Lack of follow-up negates value of case reports
Yoon K LOKE, et al.
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