Silicone breast implants: epidemiological evidence of sequelae.

Abstract

Skeptics may certainly find fault with the third study (the only one to report a significant finding) or with all or any of the statistics described. But few could argue, after examining these studies, that the relative risk for a known and well-defined connective tissue disease is likely greater than 2. Another possibility has been raised, one that calls to mind other difficult-to-study syndromes linked to exposures. In a study addressing Gulf War syndrome, signs and symptoms were often mentioned that proved difficult to describe systematically and therefore difficult to study. What if a suspected silicone exposure syndrome were so mild and transient that it did not warrant a physician visit (as in the Mayo Clinic study). receive a diagnosis (as in the Nurses' Health Study), or require admission to a hospital (as in the Danish and Swedish studies)? And if such a disorder were, in fact, mild and transient, should it merit the concern that has been shown and the compensation that has been awarded in the silicone implant litigation cases to date? We suggest that neither a well-described disorder with a relative risk of less than 2 nor a transient and mild disorder seems compatible with the number of litigants over silicone implants and the apparent seriousness of their complaints. Some 400,000 women joined in one class action suit for damages, and 170,000 joined in another. Even if there had been 2 million implants undertaken in the United States over the 3 decades in which implant surgery has been practiced (and some estimates put the number closer to 1 million), there is no conceivable way in which a relative risk of 2 or 3 (or even 4) for each of the rare syndromes reported could explain so many exposed women being affected. At most, 2200 out of 2 million unexposed women would be expected to have had any one of the listed forms of connective tissue disorders, most of which are very rare. Doubling the risk among the exposed population yields 4400, and increasing the risk 20-fold produces 44,000. At this rate, there is no way in which 400,000 litigants could all be affected. Extensions of the already-completed studies are ongoing, at least 1 of which is government funded; apparently it is thought in the United States (though not in the United Kingdom or elsewhere) that there is still room for reasonable doubt as to the supposed causal relationships. But if epidemiology is invoked in the interest of public health to prevent the many uses of silicone, the weight of the evidence abstracted here supports the inference that silicone breast implants have not been proved guilty of causing connective tissue disorders.