Judge Stewart Dalzell of the U.S. District Court for the Eastern District of Pennsylvania granted summary judgment to Novartis Pharmaceuticals Corp. in a suit that alleged the company’s eczema drug, Elidel, caused plaintiff’s lymphoma. Perry v. Novartis Pharmaceuticals Corp., 2008 WL 2683047 (E.D. Pa. July 09, 2008). Although we typically focus on appellate opinions at MassTortDefense, this well-reasoned opinion is worth a look.
The Perrys filed suit against Novartis in October, 2005 alleging that the company had failed to warn about the risks of Elidel. Their son allegedly developed eczema shortly after his birth, and a pediatrician prescribed Elidel in 2003. He was diagnosed with lymphoma a few months later.
Defendant challenged plaintiffs’ expert evidence on causation. As is frequently the case, if plaintiffs’ expert testimony does not meet the Daubert standard, summary judgment for failure of proof on causation follows. The court noted that the core issue that the jury would have to address in this case is whether Perry’s exposure to Elidel was a substantial cause of his disease. Courts in toxic tort cases often separate the causation inquiry into general causation (whether the substance is capable of causing the observed harm in general), and specific causation (whether the substance actually caused the harm a particular individual suffered). Plaintiffs’ experts did the same, each drawing conclusions about both the capacity of the drug to cause Non-Hodgkins Lymphoma (NHL) in humans and its particular effect in Perry’s case.
An expert’s journey from general causation to specific causation need not be just a two-step process. So long as, taken together, the expert is able to draw a chain of scientifically reliable causal links that meets plaintiff’s requirements under the substantive tort law, the evidence is admissible, and it will be left to the jury to establish the relative credibility of the parties’ competing experts. Where, however, the expert reports leave wide, unexplained gaps in the causal chain, the evidence is not helpful to the trier of fact and must be excluded. In Daubert terms, just as there is no fit where there is simply too great an analytical gap between the data and the opinion offered, see Soldo v. Sandoz Pharms. Corp., 244 F.Supp.2d 434, 527 (W.D. Pa. 2003) (quoting General Electric Co. v. Joiner, 522 U.S. 136, 146 (1997)), “there is also no fit when there is too great an analytical gap between an expert’s general causation conclusion and the specific causation question the jury must ultimately answer,” said the court.
One problematic gap concerned epidemiology. Although it has not been held by the Third Circuit that epidemiological studies are an indispensable element in the presentation of a prima facie drug product liability case, Lanzilotti v. Merrell Dow Pharms. Inc., 1986 WL 7832 (E.D.Pa. July 10, 1986) at *2, epidemiology is the primary generally accepted methodology for demonstrating a causal relation between a chemical compound and a set of symptoms or a disease. See Soldo, 244 F.Supp. at 532 (quoting Conde v. Velsicol Chem. Corp., 804 F.Supp. 972, 1025-26 (S.D. Ohio 1992)). Thus, while an expert’s conclusions reached on the basis of other studies could perhaps be sufficiently reliable where no epidemiological studies have been conducted, no reliable scientific approach can simply ignore the epidemiology that does exist.
A second issue concerned the state of the art. The court made clear that the non-existence of good data does not allow expert witnesses to speculate or base their conclusions on inadequate supporting science. In cases where no adequate study shows the link between a substance and a disease, expert testimony will generally be inadmissible, even if there are hints in the data that some link might exist. This may mean that early victims of toxic torts are left without redress because they are unable to prove their cases with the scientific data that currently exists. While this is a “regrettable result in those individual cases,” said the court, it is an unavoidable reality of the structure of our legal system and is necessary to protect the interests of defendants who might otherwise be subject to crippling verdicts on the basis of slender scientific evidence. As the Seventh Circuit has noted, the courtroom is not the place for scientific guesswork, even of the inspired sort. “Law lags science; it does not lead it.” Rosen v. Ciba-Geigy Corp., 78 F.3d 316, 319 (7th Cir.1996).
Focusing next on specific causation, the court noted that each plaintiff expert engaged in a differential diagnosis. MassTortDefense notes the increasing use, and misuse, by plaintiffs of so-called differential diagnosis. The process by which a doctor views symptoms and test results to rule out possible alternative diseases in the diagnostic process to arrive at a conclusion concerning what ails the patient, has morphed into a process by which experts can tell the jury what caused the condition of the plaintiff – a far different thing. Here, after finding that no other risk factor for NHL was present, the experts concluded that because the drug was the only risk factor present and because the disease is rare, plaintiff’s treatment with Elidel was a substantial factor in his presentation with the disease. However, in order to result in an admissible conclusion, a differential diagnosis should reliably rule out reasonable alternative causes of the alleged harm including idiopathic causes. Soldo, 244 F.Supp.2d at 567. Admissible expert testimony need not rule out all alternative causes, but where a defendant points to a plausible alternative cause and the doctor offers no explanation for why he or she has concluded that it was not the sole cause, that doctor’s methodology is unreliable.
Here, the differential diagnoses by plaintiff experts failed to exclude the likelihood that Perry’s lymphoma had no known cause. Most NHL cases are idiopathic, having no known cause. Courts have excluded experts’ differential diagnoses where they failed to adequately account for the likelihood that the disease was caused by an unknown factor. Doe v. Ortho-Clinical Diagnostics, Inc., 440 F.Supp.2d 465, 478 (M.D.N.C. 2006); Whiting v. Boston Edison Co., 891 F.Supp. 12 (D. Mass.1995). This is not to say, cautioned the court, that where most diagnoses of a disease are idiopathic it is impossible to prove specific causation. But in those cases, analysis beyond a differential diagnosis will likely be required.
Plaintiffs’ experts’ general causation conclusions were primarily based on animal studies and their failure to satisfactorily address epidemiology (and the gap related to dosage levels in the studies vs. plaintiff’s exposure) undermined the usefulness of those conclusions to a jury. Since plaintiffs’ experts failed to form a scientifically grounded chain of inference between their general causation finding and their specific causation finding, their opinions were excluded. Summary judgment followed.