and medical devices, dietary supplement manufacturers and distributors are not required to disclose to FDA the adverse event reports that they receive (CFSAN, 2001; OIG, 2001). As a result, an important established source of reports for medical products is not duplicated for dietary supplements, and the evolution of a concomitant culture of adverse event reporting among manufacturers and distributors is not encouraged.
The lack of manufacturer disclosure requirements is especially important given that consumers may be less likely to report adverse reactions to practitioners, a usual source of adverse event reports. A study sought to determine whether botanical remedy users would report adverse reactions to such products differently from similar adverse reactions experienced with the use of OTC medications (Barnes et al., 1998). While approximately 30 percent would consult their general practitioner irrespective of which type of ingested product was being used, and another 43 percent would not consult in either case, 26 percent would consult their general practitioner for a serious OTC-associated adverse reaction, but not for a similar adverse reaction associated with use of an herbal remedy.3
In summary, adverse event report assessment of dietary supplement ingredients is of heightened complexity and ambiguity compared with that of medical products.
Spontaneous reports entail an assumed association between the denoted adverse event and product in question, but careful evaluation of accumulated cases is needed to assess the actual strength of the association. Achieving certain proof of causality is not necessary to determine that an unreasonable or significant risk exists, especially if other types of data support the same conclusion.
Regarding numbers of cases needed for such assessment, when the medical product-adverse event relationship is stronger and the incidence of the adverse event occurring de novo/naturalistically is lower (i.e., the event
Of further significance is the international variation with respect to consumer reporting. The European Union regulatory agencies do not routinely accept drug adverse event reports from consumers that are not confirmed by a health professional, while few countries (the United States and Canada being notable exceptions) require pharmaceutical companies to submit consumer reports that they receive (CIOMS, 2001). In addition, while U.S. consumers are encouraged to report adverse events directly to FDA (FDA, 2003c), it is conceivable that the lack of encouragement for consumer reporting in other countries might negatively affect accumulation of dietary supplement-associated adverse event data on a global basis.