Documentation and reporting of adverse events are critical steps in the effort to prevent ADRs. Adverse reactions should be clearly described and documented in the medical record. This is mandated by the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) as a method for preventing serious adverse reactions from re-exposure to a medication to which a patient may be allergic or intolerant. Most adverse reactions, however, are not properly documented or reported. Despite the importance of spontaneous adverse drug reaction reporting, it is estimated that only 1 in 10 serious adverse drug reactions is reported to the FDA. Given the large number of drug prescriptions written each year in the United States, this figure most likely overestimates the number of reports.
The reason most often cited for the lack of adverse event reporting is uncertainty about the causality of an adverse reaction. Although confirmation of an ADR is ideal, it is often not feasible. The FDA readily acknowledges this limitation and continues to encourage the reporting of all suspected adverse drug reactions through its MedWatch program. Detailed instructions for reporting adverse events associated with drugs, medical devices, vaccines, and veterinary products is provided online by the FDA (http://www.fda.gov/medwatch/report/ hcp.htm). The essential components of an ADR report are listed in Table 25.6. The FDA is particularly interested in receiving reports of adverse reactions involving new chemical entities and serious reactions involving any medical product.
Adverse drug reaction data are largely drawn from spontaneous reports to the FDA or pharmaceutical manufacturers, postmarketing surveillance studies, and published case reports or case series. These sources are critical for identifying ADRs that are not detected or clearly characterized during preregistra-tion clinical trials. ADRs are least likely to be detected when they have a low incidence, when drug exposure is minimal or infrequent, when the ADR manifestation or effect has a high background frequency (e.g., common symptom due to causes other than the medication), and when a time or dose relationship is weak or absent (59).
TABLE 25.6 Essential Components of an ADR Report
• Patient demographics
• Suspected product's name and manufacturer
• Relevant history and preexisting medical conditions
• Other medications or treatments
• Detailed description of the adverse event and its management
Date of onset
Dates and times that suspected drug was started and stopped Dose, frequency, and route/method of drug administration
• Outcome of event (e.g., death, disability, prolonged hospitalization)
• Relevant laboratory tests or diagnostic findings
• Information regarding dechallenge and rechallenge
• Presence of confounding variables
Pharmaceutical manufacturers are required to report serious adverse drug events to the FDA within 15 days of receiving a report. All other reports are submitted on a quarterly basis for the first 3 years after marketing, and annually thereafter. Reports of serious adverse reactions, either during clinical trials or after drug marketing, occasionally result in FDA-mandated inclusion of "black box" warnings in the product label. These warnings usually are drug specific, but occasionally pertain to an entire pharmacological class of medications. New data relating to drug safety and efficacy also sometimes prompt the FDA to require pharmaceutical manufacturers to disseminate "dear doctor" letters to alert healthcare providers of findings that have the potential for substantial impact on public health. These and other safety notifications can be accessed at the FDA web site (http://www.fda.gov/medwatch/safety.htm).
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