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or poison control centers—constitute important sources of safety information, along with published case reports and case series about adverse events. All unsolicited reports from health professionals or consumers received by FDA via either the voluntary or mandatory route are called spontaneous reports, so classified because they are clinical observations that originate outside of a formal study (Faich, 1986). The large-scale regulatory agency safety databases are composed of adverse event information generated by reporting from all sources, including scientific literature case reports and case series; each type of product (e.g., drug, biologic, device, and dietary supplement) is represented.

While different products have aspects unique to their specific type, the principles of postmarketing safety monitoring apply to all; thus, what has been, and what will be, learned from one product realm is generally globally applicable. Dietary supplements, many of which contain biologically active ingredients, are no exception; that the guiding scientific principles for postmarketing safety surveillance have predominantly resulted from experience with pharmaceuticals (drugs and biologics) in no way invalidates their applicability to other substances, such as dietary supplement ingredients.

However, while the underlying principles for safety monitoring are globally valid, the regulatory situation of dietary supplements impacts the use of their associated adverse event reports in several ways. Unlike drugs, biologics, and medical devices, dietary supplements do not undergo premarketing evaluation for safety and efficacy by FDA, and a formal benefit/risk assessment is not performed as part of an approval process. There is no evaluation of product quality (including purity, content uniformity, and stability) prior to marketing, and there is no requirement for manufacturers to collect or report adverse events to FDA. Yet, at the same time, the threshold for concern or action for a dietary supplement is lower than for regulated medical products, as under the applicable law they are considered to be similar to foods.

In this section, the strengths and limitations of using adverse event reports for medical products in general are described, as well as how significant differences in laws and regulations impact the evaluation of adverse event reports associated with dietary supplement use.

Strengths and Limitations

The limitations of spontaneous adverse event reporting systems are well recognized, and include subjectivity and imprecision of adverse event recognition (Karch et al., 1976; Koch-Weser et al., 1977), underreporting (Chen et al., 1994; Chyka and McCommon, 2000; Rawlins, 1995), reporting biases (Sachs and Bortnichak, 1986), lack of precise exposure data (Begaud et al., 1994), and variability in report quality (Goldman, 1998). In



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