Underreporting adverse events

Limited Knowledge of Exposure and Reporting Rates in Postmarketing Data. Unlike clinical trials and electronic medical records in clinical practice, postmarketing voluntarily reported data contain limited information about the total number of patients exposed and the duration of exposure. This problem is compounded by the fact that adverse events are often underreported [2,9]. 

Underreporting of adverse events of medication is a global phenomenon. It applies to prescription and over-the-counter medicines and undoubtedly the same is likely to be true for CAM treatments. However, manufacturers of alternative treatments do not provide ongoing monitoring of the safety of their products that is comparable to that of pharmaceutical companies. 

A number of variables influence the likelihood of an adverse event being reported. These include the length of time that a product has been marketed, the market share, experience and sophistication of the population using the product, and publicity about adverse events. Currently there is little incentive for health professional reporting of adverse events, which partially imderlies the problem with underreporting. Lack of exposure data and the issue of underreporting preclude estimation of incidence rates. Causality assessment is difficult or impossible because of the quality of the data received and the lack of a comparator (control) group. Finally, comparisons of product safety cannot be directly obtained from adverse event data. 

Exposure to Asteraceous plants may also result in the development of contact dermatitis. One Serbian study has indicated that it is not unusual to detect sensitization to chamomile (Chamomilla recutita), arnica (Arnica montana), tansy (Tanacetum vulgare), and feverfew (Tanacetum parthenium) (Jovanovic et al., 2004). Contact dermatitis, along with asthma and rhinitis, may also accompany occupational exposure to chamomile (Rudzki et al., 2003) and contact dermatitis to feverfew (Hausen, 1981). Similarly, chamomile in cosmetic products can also be a cause of dermatitis (Paulsen, 2002 Rycroft, 2003). Because chamomile-containing products, particularly in shampoos and other OTC products, are so widespread, the linkage to these types of adverse events are likely underreported. Also, use of royal jelly, a thick mixture of honey, pollen, and their allergens, has been associated with several cases of bronchospasm, and topical application of concentrated forms of bee pollen (propalis) to contact dermatitis (Perharic, 1993). Milk thistle has also been known to cause urticaria (De Smet, 2004). 

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