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Content, Consistency, and Quality of Black Box Warnings

TO THE EDITOR: Elraiyah and colleagues (1) propose that adding an evidence profile would improve the usefulness of black box warnings (BBWs). Although knowing the quality of evidence supporting each warning may help prescribers gauge the strength of association between a drug and an adverse reaction, we suggest that assessing the patient's risk factors for the reaction is critical to determine the warning's applicability to an individual patient. As the authors reported, all of the BBWs that they evaluated describe the at-risk population. We have reviewed BBWs for more than 3000 prescription drugs and have noted that the content, level of detail, and number and type of adverse reactions vary widely. Some warnings, such as those about cardiovascular events and estrogen replacement therapy, are based on results from large prospective studies. Others are based on case reports or animal data (for example, those about progressive multifocal leukoencephalopathy and rituximab or teratogenicity and valganciclovir, respectively). Despite varying levels of evidence, all have strong recommendations for preventing, mitigating, or managing serious adverse reactions. Even when the evidence is of low to moderate quality (as for abacavir-induced hypersensitivity and the HLA-B*5701 allele), a patient risk assessment is standard practice (2). We agree with Elraiyah and colleagues that an implementation plan is important for facilitating safe use of drugs with BBWs. We have found that the drug label often provides detailed discussions and recommendations for addressing adverse reactions, although the information may be in several sections of the label and not necessarily contained in the BBW itself (3). The authors' findings that 96% of the warnings reviewed provided BBW-specific practice recommendations are consistent with our observations. With the increased use of electronic health information systems, we believe that integrating BBW-specific information into the electronic clinical workflow could improve the usefulness of these warnings. This information should identify the drug, its associated adverse reactions, and actions to be taken. These actions should be stratified by the steps of the medication use process, including pretreatment assessments (for example, evaluation of patient risk factors) and considerations for prescribing, dispensing, administration, monitoring, or patient counseling for the drug. Clinicians could then choose to view only action items relevant to their role in the care of the patient. Rigorously maintained data on BBWs could help provide point-of-care guidance for the safe use of drugs with these warnings.