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Recent Judicial Decisions on Specific Causation
By Lori B. Leskin
It is, of course, black letter law that to causation experts (In re Viagra Prod. Liab. cause of plaintiffs’ NAION, e.g., Id. prove a claim, a plaintiff in a product Litig., 572 F. Supp. 2d 1071 (D. Minn. 2008)), liability suit must establish that the and discovery continued on two of the MDL product at issue caused the injury suffered by cases. Pfizer subsequently moved to exclude the regarding Viagra without a scientifically the plaintiff. Causation includes both general remaining general causation expert, as well as and specific: General causation “bears on the opinions of plaintiffs’ five specific causation whether the type of injury at issue can be experts. The court granted Pfizer’s motion to Id. at 960 (“without a proper basis for caused or exacerbated by the defendant’s exclude the general causation expert’s opinion product,” while specific causation “bears on as “not sufficiently reliable” under Daubert. In whether, in the particular instance, the injury re Viagra Prod. Liab., Litig., 658 F. Supp. 2d 936 actually was caused or exacerbated by the (D. Minn. 2009). While the court recognized • Second, the experts made no effort — defendant’s product.” Ruggiero v. Warner- that the general causation opinion “effectively Lambert Co., 424 F.2d 249, 251 n. 1 (2nd Cir. ended the current litigation,” “for the sake of 2005). See also Pick v. Amer. Med. Sys., Inc., comprehensiveness,” the court additionally for plaintiffs’ NAION. Id. at 957 (Dr. 958 F. Supp. 1151, 1164 (E.D. La. 1997), aff’d considered, and granted, Pfizer’s motion to 198 F.3d 241 (5th Cir. 1999). Absent a showing exclude the five specific causation experts as of both types of causation, a plaintiff’s claims well. 658 F. Supp. 2d at 956.
the cause of plaintiffs’ NAION”), Id. necessarily fail. In re Viagra Prod. Liab. Litig., Three of the case specific experts purported at 959 (“Dr. Lee’s failure to ‘rule out’ to rely on a “differential diagnosis” to reach Plaintiffs have often assumed that if they their conclusion that Viagra caused the his differential diagnosis scientifically could overcome the general causation barrier, plaintiffs’ NAION. As the court explained: they could easily create an issue of fact on • Third, the experts did not use “any the issue of specific causation. Recently, a physician begins by “ruling in” all however, courts are giving more critical attention to the issue of specific causation, plaintiff’s injury. The physician then underlying risk factors caused Plaintiffs’ and, with increasing frequency, are excluding “rules out” the least plausible causes NAION.” Id. at 958. Rather, although This article highlights three recent court remains. The final result of a differential decisions — two involving Viagra® and one diagnosis is the expert’s conclusion that involving Seroquel® — rejecting plaintiff’s a defendant’s product caused (or did not efforts at establishing specific causation as a Viagra caused plaintiffs’ NAION.” Id. matter of law. These decisions confirm that Id. at 957, citing Glastetter v. Novartis speculative specific causation evidence is Pharm. Corp., 252 F.3d 986, 989 (8th Cir. 2001). In re VIagra Prod. LIab. LItIg.
a differential diagnosis is “presumptively In In re Viagra Prod. Liab. Litig., 658 F. Supp. admissible,” the court recognized that a Plaintiffs’ risk factors alone, caused 2d 950 (D. Minn. 2009), several plaintiffs in 2006 differential diagnosis that “fails ‘to consider plaintiffs’ NAION” (Id. at 960), or for began filing complaints against Pfizer asserting all the possible causes, or to exclude each claims that Viagra®, Pfizer’s prescription potential cause until only one remain[s], or to plaintiffs at the same time (Id. at 959). medication for the treatment of male erectile consider which of two or more non-excludable • Fourth, to the extent the experts relied dysfunction, caused them to suffer vision loss cause [is] the more likely to have caused the solely on “temporality” — the fact that from a disorder known as non-arteritic ischemic condition” is an inadequate, and inadmissible, plaintiffs’ injuries occurred in temporal optic neuropathy (“NAION”). Following expert methodology. Id., citing Turner v. Iowa Fire discovery, the court granted Pfizer’s motion Equipment Co., 229 F.3d 1202, 1208 (8th Cir. excluding three of plaintiffs’ four general 2000). The court then examined each expert’s alone to establish causation.” Id. at attempts at applying differential diagnosis and found them to be speculative and invalid. • Fifth, the court also faulted the experts Lori B. Leskin is a partner at Kaye Scholer
• First, the court held that because he for “employ[ing] a lower standard from LLP and a member of the Product Liability Liti- had excluded all of plaintiffs’ general what would be used in the medical realm” gation Group. Ms. Leskin was lead counsel for in reaching their causation conclusions. Pfizer in the Viagra cases discussed in this arti- Id., citing Marmo v. Tyson Fresh Meats, cle. Kaye Scholer also serves as counsel for As- Inc., 457 F.3d 748, 758 (8th Cir. 2006) traZeneca in the national Seroquel litigation.
was no basis to “rule in” Viagra as a LJN’s Product Liability Law & Strategy “admitted that the causation standard to adequately consider possible alternative identified no affirmative evidence of causation she employed … was a much lower causes of Guinn’s weight gain and diabetes.” and designated no experts. Rather, the plaintiff standard than medical causation”). Two Id. A “differential diagnosis that fails to take simply asserted that the claimed injury of the plaintiffs’ experts acknowledged serious account of other potential causes may was “so new there has not been sufficient they were applying a less rigorous be so lacking that it cannot provide a reliable scientific testing to establish the causality of standard in reaching their opinions in basis for an opinion on causation.” Id. at 1253, the use of [Viagra] and a hemorrhage.” Id. at the litigation than they would in their citing Westberry v. Gislaved Gummi AB, 178 3. In response to Pfizer’s motion for summary ordinary medical practice. judgment, the plaintiff turned to the doctrine • Finally, the court rejected one expert’s Significantly, the court rejected the expert’s of res ipsa loquitur. supposed reliance on the “Bradford reliance on temporal proximity to explain why This doctrine allows a plaintiff to assume Hill criteria” for his specific causation Seroquel would be the most likely cause of the negligence where an injury occurred under opinion because that test is “used plaintiff’s diabetes. The expert tried to explain circumstances that would not normally occur to establish general causation from why the plaintiff’s “numerous other risk factors in the absence of negligence. Id. However, as epidemiological studies – they are not for diabetes” were not the sole cause because the court recognized, “the mere mention of res used to establish specific causation.” “they remained constant” while the plaintiff ipsa loquitur … does not relieve a plaintiff of Id. at 958.
took Seroquel, but did “not explain why having the burden imposed by the law.” Id. As with an In addition, the court excluded two of the a stable risk profile makes it unlikely that expert’s invocation of “differential diagnosis,” plaintiffs’ experts as “unqualified” to render preexisting risk factors caused” the plaintiff’s under res ipsa loquitur, a plaintiff “bear[s] the an opinion as to the cause of the plaintiffs’ illness, particularly where it was not disputed burden of excluding reasonable explanations NAION. The court held that the assessment of that those risk factors “put her at an extremely for the accident other than defendant’s the cause of the plaintiffs’ visual injuries fell high risk for diabetes.” Id. at 1254: negligence.” Id. Applying these principles to “outside the realm” of these experts’ — one Mr. Ridgeway’s claims, the court rejected the an epidemiologist but not a medical doctor, conclude that all risk factors for a disease plaintiff’s efforts to invoke the theory. and the other a treating urologist of one of are substantial contributing factors in its The court recognized that res ipsa loquitur the plaintiffs — expertise. Id. at 960-61.
only applies where the circumstances are In excluding the specific causation experts’ “so unusual” that they would “not typically opinions, the court looked past the rote disease does not make it an actual cause occur in the absence of negligence.” Id. at recitation from the experts that they held their *4. Mr. Ridgeway’s use of Viagra for over opinions to a “reasonable degree of medical 10 years followed “on one occasion” by a certainty after reviewing all of the evidence.” together to cause diabetes, Dr. Marks was “relatively common medical injury with no Rather, the court recognized its role as more still required to provide some analysis of clear association with Viagra” was not such than a rubber stamp, and its obligation to why she concluded that, more likely than a circumstance. Id. The plaintiff’s admission “exercise its gatekeeper role to ensure that not, Seroquel substantially contributed to that his theory of causation was “speculative” the opinions that [plaintiffs’ experts have] Guinn’s weight gain and such weight gain further “undercuts the argument that res ipsa offered are sufficiently reliable to make their was among the factors that substantially way to a jury.” Id. at 959.
Moreover, the plaintiff failed to exclude guInn V. astraZeneca Pharms. LP
Id. (citations omitted). Having failed to other possible causes for the plaintiff’s stroke, In Guinn v. AstraZeneca Pharms. LP, explain properly the bases for ruling out other including the plaintiff’s history of hypertension, 602 F.3d 1245 (11th Cir. 2010), an expert’s potential causes of the plaintiff’s injury, Dr. the “leading cause of hemorrhagic stroke.”
questionable use of differential diagnosis was Marks’ opinion was held inadmissible. Moreover, Id. Thus, the court refused to presume fault
also reviewed by the Eleventh Circuit. Guinn the court found that Dr. Marks did not “conduct “when plaintiffs themselves admit that their
was one of the first cases in the Seroquel standard diagnostic techniques she normally theory of causation is so novel that no one
MDL to reach the Daubert motion stage on used to rule out potential alternative causes.” has yet had a chance to study it.” Id.
specific causation. The MDL was formed in Id. Thus, as with the Viagra litigation, the expert
the Middle District of Florida in July 2006, failed to “employ[ ] in the courtroom the same ConClusion
and has included claims that AstraZeneca’s level of intellectual rigor that characterizes
In sum, challenges to the reliability and anti-psychotic medication, Seroquel, caused the practice of an expert in the relevant field.” sufficiency of plaintiffs’ specific causation plaintiffs to develop diabetes. Id., citing Kumho Tire Co. v. Carmichael, 526 evidence are as important as challenges to In Guinn, following a Daubert hearing, U.S. 137, 152 (1999). Given the failings of Dr. general causation. Where general causation the district court excluded the plaintiff’s Marks’ opinion, ultimately the Eleventh Circuit is established — or at least considered expert for failing “to articulate any scientific affirmed the decision to exclude her opinion as sufficiently reliable for Daubert purposes — a methodology for assessing whether, and to “mere speculation.” Id. at 1257.
specific causation challenge may be the only what extent, Seroquel contributed to Guinn’s rIdgeway V. PfIZer Inc.
avenue for winning on causation as a matter weight gain and diabetes,” 598 F. Supp. 2d Finally, in another decision involving Viagra, of law. Courts have closely analyzed experts’ 1239, 1243 (M.D. Fla. 2009), and granted Ridgeway v. Pfizer Inc., 2010 WL 1729187 invocation of differential diagnosis, and have summary judgment to defendant. On appeal, (E.D.La. April 27, 2010), the court reaffirmed rejected opinions where the application lacks the Eleventh Circuit affirmed.
the need for admissible expert medical reliable scientific methodology or factual Like the district court in the Viagra evidence to support specific causation. In bases. The recent Viagra and Seroquel opinions litigation, the Eleventh Circuit recognized Ridgeway, the plaintiff suffered a hemorrhagic discussed herein underscore the importance that “[w]hen properly conducted, differential stroke following use of Viagra. During the of closely questioning the plaintiffs’ specific diagnosis can be a reliable methodology course of discovery, none of the plaintiff’s causation evidence. under Daubert.” 602 F.3d at 1253. However, treating physicians attributed the plaintiff’s simply claiming that an expert conducted a stroke to his use of Viagra. To the contrary, differential diagnosis, without more, “does at least one of the doctors considered such a not establish the reliability of his techniques causal relationship to be “totally ridiculous.” or the validity of his conclusions.” Id. 2010 WL 1729187, at *2. None of the doctors Reprinted with permission from the September 2010 edition of Looking at the expert at issue in the could even identify any medical literature the Law JouRnaL newSLetteRS. 2010 aLM Media Properties, LLC. all rights reserved. Further duplication without Guinn case, Dr. Marks, the court affirmed the that would establish a causal link. Id. permission is prohibited. For information, contact 877.257.3382 district court’s exclusion “because she failed In the face of this testimony, the plaintiff or [email protected]. #055081-10-10-05

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