A strategy for regulatory action when new adverse effects of a licensed product emerge.

Regulatory agencies grant product licences (marketing authorizations) for medicinal products in the light of evidence that the balance between benefit and harm in the population is favourable. Here we consider a framework for allowing regulatory agencies to make rational decisions when reviewing product licences in the light of new information about harms that change that balance. The regulator can revoke the product licence, restrict the product's availability or change the 'label' in different ways. We examine the features of the adverse effect that may be relevant in making the decision: namely, individual differences in susceptibility; the possibility of monitoring; and the availability of protective strategies. The balance of benefit and harm, and the time-course and dose relation of the adverse effect play important roles in the decision-making process. We set out how these factors can help determine the logical response to new information on the balance between benefit and harm, and provide a series of relevant examples. We believe that when regulatory agencies have to decide how to amend the product licence of a drug when new serious adverse effects cause concern, they would find it useful to adopt a framework of this kind, using different strategies for different cases. Our proposed framework could also be useful in risk management planning during drug development.

Systematic reviews of adverse effects: framework for a structured approach.

BACKGROUND: As every healthcare intervention carries some risk of harm, clinical decision making needs to be supported by a systematic assessment of the balance of benefit to harm. A systematic review that considers only the favourable outcomes of an intervention, without also assessing the adverse effects, can mislead by introducing a bias favouring the intervention. Much of the current guidance on systematic reviews is directed towards the evaluation of effectiveness; but this differs in important ways from the methods used in assessing the safety and tolerability of an intervention. A detailed discussion of why, how and when to include adverse effects in a systematic review, is required. METHODS: This discussion paper, which presupposes a basic knowledge of systematic review methodology, was developed by consensus among experienced reviewers, members of the Adverse Effects Subgroup of The Cochrane Collaboration, and supplemented by a consultation of content experts in reviews methodology, as well as those working in drug safety. RESULTS: A logical framework for making decisions in reviews that incorporate adverse effects is provided. We explore situations where a comprehensive investigation of adverse effects is warranted and suggest strategies to identify practicable and clinically useful outcomes. The advantages and disadvantages of including observational and experimental study designs are reviewed. The consequences of including separate studies for intended and unintended effects are explained. Detailed advice is given on designing electronic searches for studies with adverse effects data. Reviewers of adverse effects are given general guidance on the assessment of study bias, data collection, analysis, presentation and the interpretation of harms in a systematic review. CONCLUSION: Readers need to be able to recognize how strategic choices made in the review process determine what harms are found, and how the findings may affect clinical decisions. Researchers undertaking a systematic review that incorporates adverse effect data should understand the rationale for the suggested methods and be able to implement them in their review.

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

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.

Unintended events following immunization with MMR: a systematic review.

Public debate over the safety of the trivalent measles, mumps and rubella (MMR) vaccine and the drop in vaccination rates in several countries persists despite its almost universal use and accepted effectiveness. We carried out a systematic review to assess the evidence of unintended effects (beneficial or harmful) associated with MMR and the applicability of systematic reviewing methods to the field of safety evaluation. Eligible studies were comparative prospective or retrospective on healthy individuals up to 15 years of age, carried out or published by 2003. We identified 120 articles satisfying our inclusion criteria and included 22. MMR is associated with a lower incidence of upper respiratory tract infections, a higher incidence of irritability, similar incidence of other adverse effects compared to placebo and is likely to be associated with benign thrombocytopenic purpura (TP), parotitis, joint and limb complaints and aseptic meningitis (mumps Urabe strain-containing MMR). Exposure to MMR is unlikely to be associated with Crohn's disease, ulcerative colitis, autism or aseptic meningitis (mumps Jeryl-Lynn strain-containing MMR). The design and reporting of safety outcomes in MMR vaccine studies, both pre- and post-marketing, are largely inadequate. The evidence of adverse events following immunization with MMR cannot be separated from its role in preventing the target diseases.