This post and the previous one are an expansion upon a post that I wrote with Dr. David Schwartz, of Innovative Science Solutions, LLC. Dr. Schwartz is a talented scientist with whom I had the privilege and pleasure to work at McCarter & English, before he left to become an independent scientific consultant. Dr. Schwartz is one of the founding partners of his firm, which focuses on helping lawyers with the scientific issues in complex health effects litigation. Our earlier post can be found on the Courtroom View Network’s website. “Guest Analysis: Key Takeaways from Recent Talc Powder ‘Science Day’ Hearing in California,” Courtroom View Network (Mar 24, 2017).
Talc Science Goes Bicoastal
This year, two trial judges have entertained Science Days in talc cases, on both coasts of the United States. In the federal talc litigation, MDL 2738, Judge Freda L. Wolfson conducted a Science Day on January 26, 2017. In the coordinated California state court talc cases, Judge Maren E. Nelson, of the Superior Court of California, Los Angeles County, conducted a Science Day, on March 7, 2017.
Federal Talc MDL 2738
In the federal cases, Johnson & Johnson, one of the defendants, initiated the Science Day, in November 2016, when it asked Judge Wolfson to set aside a day in “which the parties and their experts can outline their positions/arguments regarding the medical and science issues at play.” In Case Management Order No. 1 (Jan. 23, 2017), Judge Wolfson apparently agreed, and the parties had their talc Science Day on January 26, 2017. The Science Day took up over five hours of presentations to Judge Freda L. Wolfson, and Judge Lois H. Goodman.
California Coordinated Docket
In the California cases, plaintiffs’ counsel filed a formal motion, in early December 2016, to request a Science Day tutorial. The plaintiffs’ motion requested that each side be permitted two hours to present their views of the scientific evidence in support of their litigation positions on causation and liability in talc ovarian cancer cases. The plaintiffs argued that a Science Day would be “significant benefit to the Court and the parties.” Judge Nelson granted the request, and held Science Day on March 7, 2017.
Courtroom View Network (CVN)
The proceedings in California were recorded videographically, and are available through Courtroom View Network (CVN). Johnson & Johnson opposed televising the Science Day proceedings, on the procedural ground that CVN had not filed and served the appropriate motion. Johnson & Johnson also argued a substantive ground that the proceedings were not a formal trial, and that televising “would not confer any benefit on the public, the parties, or the Court, let alone one that outweighs the significant concerns posed by such a broadcast.”
Whatever the merits of J & J’s procedural ground, its substantive grounds seem dubious. The importance of the Science Day proceedings transcends the pecuniary interests of the parties to the litigation. First, the presentations provide the empirical bases for other courts and lawyer to evaluate the procedures employed. Second, lawyers and judges generally, outside the talc litigation, can learn a great deal from the strengths, weaknesses, and mistakes made by the participants in the televised proceedings. Many of the scientific issues that pervade the talc litigation recur frequently in other mass tort litigations in the United States and abroad. Finally, and perhaps most important, the talc litigation involves litigation claims of huge import to the public generally. For better or worse, litigation has become an adjunct to regulation in the United States. If the plaintiffs’ claims are true, then there has been a serious failure of national and international regulatory agencies and scientific organizations in evaluating the evidentiary record. If the defendants’ claims are true, then the plaintiffs’ lawyers have misunderstood and distorted the basic process of synthesizing evidence and arriving at conclusions of causation. More important, it behooves the public to understand why one side is wrong.
Evaluation of the California Talc Litigation Science Day
The presentation by the plaintiff lawyers was eerily reminiscent of the scientific case made by plaintiffs in the silicone breast implant ligation. Their arguments ranged from highlighting anecdotal evidence to emphasizing the implicit sinister nature of talc migration from the vaginal opening to the ovaries. Plaintiff counsel focused heavily on the alleged role of talc in the inflammatory process and strong (unsubstantiated) implications that anything that enhances inflammation must necessarily cause cancer.
As one would expect, plaintiff counsel placed strong emphasis on the published epidemiological studies linking talc exposure to ovarian cancer. It is important to highlight that the majority of the studies showing an association between talc and ovarian cancer came from case-control studies by design (as opposed to a cohort design). Plaintiff counsel offered very little distinction between these two study designs and, instead tried to make the case that the sheer volume of studies made their argument..
Finally, it should be noted that at many times throughout the plaintiff presentations, the presenter veered off into non-scientific, ad hominem attacks against the industry and/or activities that they tried to paint as venal or unseemly. Defense counsel made objections throughout that seemed to be based upon first amendment protections for the defendants’ ability to speak to agencies about the scientific evidence. For example, the last presenter for the plaintiffs described alleged industry “lobbying” efforts at NTP. Defense counsel objected on first amendment grounds, and the judge semi-sustained the objection on the basis that it had little or nothing to do with the science. The plaintiffs’ emphasis on “lobbying” contained no examples of misrepresentations of scientific data. See “Talc Litigation in Missouri – Show Me the Law and the Evidence” (Feb. 24, 2017).
In general, the defense presentations were more structured, coherent, substantial, and rigorously scientific. For example, unlike the plaintiffs’ graphics, many of the defense slides could stand on their own in a scientific or medical society presentation. The defense lawyers attempted to provide a solid foundation for the judge on the different types of ovarian cancer as well as the myriad uncertainties that exist in terms of the known causes of the condition. Many of the slides contained direct quotes from notable scientists and regulators on topics that were directly relevant to answering critical questions in the litigation.
Epidemiology and Specific Causation
Nevertheless, the defense presentations were not without their problems. Consider the following quote from an article by Graham Colditz, used in one of the defense powerpoint slides:
“The fundamental object of epidemiology is to estimate the population average risk of the disease. Risk is a population measure, not an individual disease measure.”
Colditz has served as an expert witness on epidemiology for plaintiffs in talc and other litigations, and the defense no doubt believed that they could make their point in a rhetorically powerful way by quoting him. The problem starts with the quote’s failure to make the defense’s point. Risk is a measure or relative proportions in the sample, to be used to estimate the population measure. To say that it is a group measure, however, does not mean that there are no reasonable inferences from the group measure to the individual member of the sample or population.
The defense seems to want to argue that even there were an increased risk not explained by chance, bias, or confounding, that measure of risk does not tell us anything about what caused an individual claimant’s ovarian cancer.
A fuller quotation might even have helped the defense because Colditz seems intent on undermining not just the use of group measures of risk as an individual variable, but also the use of the measure to support an inference about individuals:
“The fundamental object of epidemiology is to estimate the population average risk of disease. Risk is a population measure, not an individual measure. Epidemiology does not estimate individual levels of risk, nor does it perfectly predict individual likelihood of disease. As noted by Rose, epidemiology does not describe why an individual case of cancer arises in the population but rather the population burden of cancer.14 In his article in this issue of the Journal, Begg ignores this principle and uses the term “risk” as an individual-level variable.15”
The fuller quotation points to a disagreement in which another epidemiologist was willing to use risk to describe individual attribute, but more to the point is that Colditz’s assertion is that risk is a group measure.
Colditz, at least in this article, does not claim that the group measure of risk was irrelevant to prospective individual predictions or retrospective individual attributions. Interestingly, Graham Colditz has elsewhere asserted that an increased risk of disease cannot be translated into the “but-for” standard of causation:
“Knowledge that a factor is associated with increased risk of disease does not translate into the premise that a case of disease will be prevented if a specific individual eliminates exposure to that risk factor. Disease pathogenesis at the individual level is extremely complex.”
Defense may have wanted to highlight this assertion even recognizing that it is controversial, and quite dependent upon the magnitude of the measured risk.
In attempting to make their point with a quote from plaintiffs’ own expert (Dr. Graham Colditz), the defense oversimplified a much more complex issue. While increased or relative risk is indeed a measure or incidence rates used to estimate rates in the broader population, this aspect of relative risk as a measure does not mean that there are no reasonable inferences that can be made from the group measure to the individual member of the sample or population. The defense seems to want to make the seemingly unreasonable point that even if an increased risk were appropriately demonstrated by the epidemiology, that that measure of risk does not tell us anything about what caused an individual claimant’s ovarian cancer. This point might be correct when the magnitude of the increased risk is small (as is alleged in the talc ovarian cancer litigation), but the sweeping generality of the defense’s assertion is jarring.
Back in the 1960s and 1970s, tobacco companies attempted to rebut inferences of individual causation, despite scientific consensus on general causation, and relative risks of 20 to 30, and more for lung cancer in smoking versus non-smoking groups. The tobacco companies’ claim of the irrelevancy of epidemiology to inferring specific causation was not particularly credible when the population attributable risk was 95 percent and greater.
Even at lower relative risks, measures of risks in epidemiologic studies and clinical trials are used to predict individual responses to treatments, to life style interventions, and to life style and other risk factors. Of course, there is always potential heterogeneity in the sample and in the population, which should be acknowledged, but when the studies are multivariate, with inclusion of the known causes and potential risk factors, then scientists and physicians routinely use these measures of risks and benefits in groups to make predictions about individuals.
Consider a man, seriously overweight, who goes to see his internist. His physician tells him,
“look in populations of overweight men, just like yourself, more men die of heart attack and stroke, and they die of these diseases at an early age, and suffer more morbidity and disability from them, then in groups of men who are not overweight, but don’t worry, that has NOTHING to do with you. We don’t know your risk, so go right on eating candy bars for breakfast, and studiously avoiding exercise.”
Of course, no sane, competent physician would advise the obese patient in this manner. Now, I understand rhetorically why the defense might want to capitalize on Colditz’ statement, but the end result appears to mislead the intended audience. The rejection of probabilistic inferences is still occasionally sanctioned by courts, but more typically, such inferences are permitted when not conjectural.
Defense’s Misleading Claim that Case-Control Studies are Smaller than Cohort Studies
In its Science Day presentation, the defense asserted that a disadvantage of case-control studies is, among other things, their “small size.” In the same vein, the defense claimed that an advantage of cohort studies is their “large size.” The defense provided no supporting citations for its contention about the relative size of the two kinds of analytical epidemiologic studies.
In his oral comments, the defense presenter notes the size disparity between the case-control and the cohort studies as a reason to distrust the results of the case-control studies on talc exposure and ovarian cancer. The presenter leans in and says that the cohort studies are huge, some with hundreds of thousands of women.
Now there are important qualitative differences between case-control and cohort studies, with respect to recall bias and the validity of control groups. To be sure, and fair, the defense made these points accurately. The defense’s invidious comparison of size of the two types of studies ignores that case-control studies are statistically much more efficient.
As the defense presented the matter, case-control studies are placed lower on the “hierarchy of evidence” than cohort studies. For this point, the defense did present a supporting citation, and their claim is generally correct, but epidemiologists recognize that a well-conducted case-control study may well trump a cohort study. Case-control studies are often ranked below cohort studies because of greater potential for systematic bias, the inherent difficulty in selecting appropriate controls, and because the measure of risk in the form of an odds ratio is at best an estimate of the relative risk. The sizes of the “cases” group in a case-control study and the cohort in a cohort study are not a valid comparison.
A case-control study may be based upon hundreds of cases of ovarian cancer, a size that would require a huge cohort study. Furthermore, the size of the cohort study can be highly misleading because recruitment and inception into the cohort often takes place at a young age, when the rate of ovarian cancer is very low. The efficiency of the case-control study design is reflected in the narrow confidence intervals seen in many of the published papers. Some of these confidence intervals are as narrow as those generated by analysis of data from “larger” cohort studies. The size is ultimately related to the precision of the various studies’ point estimates of measured risk, not to the accuracy of their measurements. The statistical efficiency of the ovarian cancer talc case-control studies becomes an important when rare disease subtypes are considered, or when the interaction between genotype, exposure, and cancer outcomes needs to be considered.
Synthesis of Evidence for Judgments of Causation
Finally, it seems that neither the defense nor the plaintiffs adequately incorporated into their presentations the important concept of causal inference (or how evidence from disparate sources is synthesized into a judgment of causation, or into a rejection of such a claim). Specifically, counsel never explicitly set forth the importance of the Bradford Hill factors, or the techniques of proper and rigorous systematic review methodologies. The defense did touch upon many of the key considerations of the Bradford Hill factors as they applied to the relevant data, but there was no discussion of how these factors are considered after the identification of an association that is not likely the result of bias and that is beyond the play of chance. With respect to meta-analysis, both sides provided no guidance or insight into the problems that arise in conducting, reporting, and interpreting quantitative syntheses of a body of epidemiologic studies.
The Trial Court’s Role
Most trial judges, sadly, come to cases such as the talc ovarian cancer cases without any training in statistics, epidemiology, toxicology, or an adequate understanding of the role that clinical medicine plays (or does not play) in assessing important questions of causation. Judge Nelsen seemed to listen carefully, but asked few questions to suggest that Her Honor understood the discrepancy in statements made in the parties’ presentation.
Perhaps a starting point for Science Day should be an Order that sets out the procedures for the Day, as well as a statement: “The Court has read and studied the relevant chapters in the Reference Manual on Scientific Evidence (3d ed. 2011), and all materials submitted by the parties. The parties should not recreate a tutorial that covers material in the Reference Manual, unless they wish to contest its contents. Specific references to the Manual, in connection with the parties’ presentation would be very helpful to the Court.”
In re Johnson & Johnson Talcum Powder Products Marketing, Sales Practices & Prods. Liab. Litig., No. 16-2738 (D.N.J.)