Establishing causation — general and specific — is an always-critical issue in any case involving an alleged chemical- or product-caused disease or medical condition. Proof of such invariably involves expert testimony, and the extent to which the defense can challenge the admissibility of the plaintiff’s proffered expert causation testimony is a significant issue. A recent decision from the New York Appellate Division, Ratner v. McNeil-PPC, Inc., No. 48820/02 (N.Y. Sup. Ct. App. Div., Nov. 22, 2011), 2011 NY App Div. LEXIS 8400, provides additional support for manufacturers of pharmaceuticals, medical devices, and other products in making such a challenge.
In Ratner, the plaintiff sought to establish that her long-term use of therapeutic doses of acetaminophen caused her to develop liver cirrhosis. The plaintiff’s experts, in making such a link, relied primarily on a few observational case studies. The defendant made a motion, under the prevailing Frye test applicable in New York, to exclude the plaintiff’s expert testimony on the grounds that the plaintiff’s experts’ causation theory did not meet the “general acceptance” standard for admissibility under New York law. The trial court granted the defendant’s motion and, on appeal, the New York Appellate Division, Second Department, upheld the exclusion of plaintiff’s experts.
The key issue presented to the Second Department was whether the plaintiff’s experts’ reliance on observational case studies was sufficient proof of causation to withstand the defendant’s admissibility challenge. Unlike more rigorous forms of epidemiological proof, such as randomized trials or cohort or case-control studies, case reports and case series are generally descriptions of observational data obtained from one or a small number of subjects without any comparison or control subjects. As a result — and as the Ratner court recognized — “‘courts have recognized that … observational studies or case reports are not generally accepted in the scientific community on questions of causation.’”
The plaintiff sought to overcome this weakness by arguing that her experts should be permitted to extrapolate from the case reports on which they relied. However, while recognizing that “deductive reasoning or extrapolation, even in the absence of medical texts or literature that support a plaintiff’s theory of causation under identical circumstances, can be admissible if it is based upon more than mere theoretical speculation or scientific hunch[,]” the Ratner court nevertheless concluded there was “‘simply too great an analytical gap between the data and the opinion proffered[.]’” Ultimately, the Ratner court concluded that the “case studies relied upon by the plaintiff constitute merely observational data which are of a lesser caliber than controlled clinical studies from which results can be reviewed and verified.” And, because the case studies themselves did not unequivocally link acetaminophen use to the observed liver cirrhosis reported therein, the plaintiff’s failure to “put forward any clinical or epidemiological data or peer reviewed studies showing that there is a causal link between therapeutic use of acetaminophen and liver cirrhosis” required the preclusion of the plaintiff’s experts.
The Ratner decision represents another favorable opinion on which a defendant seeking to challenge a plaintiff’s experts can rely, particularly in those jurisdictions that employ the Frye standard for expert admissibility.
If you have questions about how this may impact your business, please contact a member of the Goldberg Segalla Product Liability Practice Group.