Opinion ID: 212992
Heading Depth: 3
Heading Rank: 2

Heading: Epidemiological Evidence

Text: As to the epidemiological evidence on which Dr. Smith based his opinion in part, the court held that the published articles on which Dr. Smith relied did not support his opinion, and that in any event, the evidence was not statistically significant. On these grounds, the court rejected Dr. Smith's conclusion that the available epidemiological evidence offered some support for an inference of causation. In concluding that the papers cited by Dr. Smith did not support his opinion, the court reasoned that Dr. Garabrant convincingly demonstrated, especially with respect to the Golomb and Travis papers, that Dr. Smith's conclusions that there was a positive association between exposure to benzene and APL were based on faulty calculations of odds ratios. Milward, 664 F.Supp.2d at 149. An odds ratio represents the difference in the incidence of a disease between a population that has been exposed to benzene and one that has not. In Dr. Garabrant's opinion, Dr. Smith should have used the incidence rate of APL for the general population as a baseline, rather than the rate for non-benzene-exposed workers. In the Daubert hearing and in his supplemental report, however, Dr. Smith explained that he disagreed with Dr. Garabrant on this point, but that in any event, the odds ratio was still elevated, consistent with an inference of causation. Where, as here, both experts' opinions are supported by evidence and sound scientific reasoning, the question of who is right is a question for the jury. [17] The court explained, however, that even if some of the data reported in the various studies could be properly understood to suggest a positive association, the findings are not statistically significant, id., and that although epidemiological evidence is not always essential, the defendants were correct that sound epidemiological studies are ordinarily needed to confirm, by consistent observation, an hypothesis of causation, id. at 148. In context, the district court read too much into the paucity of statistically significant epidemiological studies. The absence of peer-reviewed epidemiological studies does not, as defendants contend, make it almost impossible for Dr. Smith's opinion to be admissible. Epidemiological studies are not per se required as a condition of admissibility regardless of context. See Rider v. Sandoz Pharm. Corp., 295 F.3d 1194, 1198 (11th Cir.2002) (It is well-settled that while epidemiological studies may be powerful evidence of causation, the lack thereof is not fatal to a plaintiff's case.); Restatement § 28 reporters' note cmt. c(3) (listing federal circuit cases holding that epidemiological data is not necessary). Nor are such studies treated as always essential in the relevant scientific communities. To be clear, this is not a situation in which the available epidemiological studies found that there is no causal link, or even one in which no cases of APL were found among benzene-exposed workers. Cf. Norris v. Baxter Healthcare Corp., 397 F.3d 878, 882 (10th Cir.2005) (holding that epidemiological studies are not required to prove causation, but that a substantial body of epidemiological evidence challenging causation cannot be ignored); Allen v. Pa. Eng'g Corp., 102 F.3d 194, 197 (5th Cir.1996) (finding it significant that numerous reputable epidemiological studies covering in total thousands of workers indicated that there was no causation). Rather, this is a case in which there is a lack of statistically significant epidemiological evidence, and in which the rarity of APL and difficulties of data collection in the United States make it very difficult to perform an epidemiological study of the causes of APL that would yield statistically significant results. [18] Dr. Smith estimated that in order to obtain statistically significant results, one would need hundreds of thousands of highly exposed workers, the same number of controls, and millions of dollars in funding. The court erred in treating the lack of statistical significance as a crucial flaw. See Collagen Corp., 161 F.3d at 1229 (finding that the district court placed too much emphasis on lack of epidemiological studies where such studies would be almost impossible to perform); see also Primiano, 598 F.3d at 566-67 (noting that peer-reviewed studies are not necessary, especially when there are good reasons why such studies have not been performed). Under these circumstances, the court erred in holding that Dr. Smith's attempt to support his conclusion with data that concededly lacks statistical significance was a deviation from sound practice of the scientific method that provided grounds for exclusion. Milward, 664 F.Supp.2d at 149. The court's evaluation of the epidemiological evidence is also in tension with the weight of the evidence methodology. Dr. Smith explained that his citation to epidemiological data was meant to challenge the theory that benzene exposure could not cause APL, and to highlight that the limited data available was consistent with the conclusions that he had reached on the basis of other bodies of evidence. He stated that [i]f epidemiologic studies of benzene-exposed workers were devoid of workers who developed APL, one could hypothesize that benzene does not cause this particular subtype of AML. The fact that, on the contrary, APL is seen in studies of workers exposed to benzene where the subtypes of AML have been separately analyzed and has been found at higher levels than expected suggested to him that the limited epidemiological evidence was at the very least consistent with, and suggestive of, the conclusion that benzene can cause APL. The court rejected Dr. Smith's reasoning, stating that a `suggestion' may give rise to a plausible hypothesis, but not a reliable inference. Milward, 664 F.Supp.2d at 149. But as noted above, this is inconsistent with the scientifically accepted methodology employed by Dr. Smith. Dr. Smith did not infer causality from this suggestion alone, but rather from the accumulation of multiple scientifically acceptable inferences from different bodies of evidence.