Slemp Trial Part 4 – Graham Colditz

The Witness

Somehow, in opposition to two epidemiologists presented by the plaintiff in Slemp, the defense managed to call none. The first of the plaintiffs’ two epidemiology expert witnesses was Graham A. Colditz, a physician with doctoral level training in epidemiology. For many years, Colditz was a professor at the Harvard School of Public Health. Colditz left Harvard to become the Niess-Gain Professor at Washington University St. Louis School of Medicine, where he is also the Associate Director for Prevention and Control at the Alvin J. Siteman Cancer Center.

Colditz is a senior epidemiologist, with many book and article publications to his credit. Although he has not published a causal analysis of ovarian cancer and talc, Colditz was an investigator on the well-known Nurses’ Health Study. One of Colditz’s publications on the Nurses’ cohort featured an analysis of talc use and ovarian cancer outcomes.

Although he is not a frequent testifying expert witness, Colditz is no stranger to the courtroom. He was a regular protagonist in the estrogen-progestin hormone replacement therapy (HRT) litigation, which principally involves claims of female breast cancer. Colditz has a charming Australian accent, with a voice tremor that makes him sound older than 63, and perhaps even more distinguished. He charges $1,500 per hour for his testimonial efforts, but is quick to point out that he has given thousands to charity. At his hourly rate, we can be sure he needs tax deductions of some kind.

In discussing his own qualifications, Colditz was low-key and modest except for what seemed like a strange claim that his HRT litigation work for plaintiffs led the FDA to require a boxed warning of breast cancer risk on the package insert for HRT medications. This claim is certainly false, and an extreme instance of post hoc ergo propter hoc. Colditz gilded the lilly by claiming that he does not get involved unless he believes that general causation exists between the exposure or medication and the disease claimed. Since he has only been a plaintiffs’ expert witness, this self-serving claim is quite circular.

The Examinations

The direct and cross-examinations of Dr. Colditz were long and tedious. Most lawyers are reluctant to have an epidemiologists testify at all, and try to limit the length of their examinations, when they must present epidemiologic testimony. Indeed, the defense in Slemp may have opted to present a clinician based upon the prejudice against epidemiologists testifying about quantitative data and analysis. In any event, Colditz’s direct examination went not hours, but days, as did the defense’s cross-examination.

The tedium of the direct examination was exacerbated by the shameless use of leading, loaded, and argumentative questions by plaintiff’s counsel, Allen Smith. A linguistic analysis might well show that Smith spoke 25 to 30 words for every one word spoken by Colditz on direct examination. Even aside from the niceties of courtroom procedure, the direct examination was lacking in aesthetic qualities. Still, it is hard to argue with a $110 million verdict, which cries out for explanation.

There were virtually no objections to Smith’s testifying in lieu of Colditz, with Colditz reduced to just “yes.” Sometimes, Colditz waxed loquacious, and answered, “yes, sir.” From judicial responses to other objections, however, it was clear that the trial court would have provided little control of the leading and argumentative questions.

Smith’s examination also took Colditz beyond the scope of his epidemiologic expertise in to ethics, social policy, and legal requirements of warnings, again without judicial management or control. We learned, over objection, from Colditz of all witnesses that the determination of causation has nothing to do with whether a warning should be given.

The Subject Matter

Colditz was clearly familiar with the subject matter, and allowed Smith to testify for him on a fairly simplistic level. The testimony was a natural outgrowth of his professional interests, and Colditz must have appeared to have been a credible expert witness, especially in a St. Louis courtroom, given that he was in a leadership role at the leading cancer center in that city.

With Smith’s lead, Colditz broached technical issues of bias evaluation, meta-analysis and pooling, which would never be addressed later by a defense expert witness at an equal level of expertise, sophistication, and credibility. Colditz offered criticisms of the Gonzalez (Sister Study) and the latency built into the observation period of that cohort, and he introduced the concept of Berkson bias in some of the case-control studies. Neither of these particular criticisms was rebutted in the defense case, again raising the question whether the defense expert witness, Dr. Huh, a clinician specializing in gynecologic oncology, was an appropriate foil for the line up of plaintiffs’ expert witness. Dr. Colditz was able to talk authoritatively (and in some cases misleadingly) about issues, which Dr. Huh could not contradict effectively, even if he were to have tried.

Colditz characterized his involvement in the talc cases as starting with his conducting a systematic review, undertaken for litigation, but still systematic. As a professor of epidemiology, Colditz should know what a systematic review is, although he never fully described the process on either direct or cross-examinations. No protocol for the systematic review was adduced into evidence. Sadly, the defense expert witness, Dr. Huh, never stated that he had done a systematic review; nor did he offer any criticisms of Dr. Colditz’s systematic review. Indeed, Huh admitted that he had not read Colditz’s testimony. In general, observing Colditz’s testimony after having watched Dr. Huh testify shouted MISMATCH.

The Issues

Statistical Significance

The beginning point of a case such as Slemp, involving a claim that talc causes ovarian cancer, and that it caused her ovarian cancer, is whether there is supporting epidemiology for the claim. As Sir Austin Bradford Hill put it over 50 years ago:

Disregarding then any such problem in semantics we have this situation. Our observations reveal an association between two variables, perfectly clear-cut and beyond what we would care to attribute to the play of chance. What aspects of that association should we especially consider before deciding that the most likely interpretation of it is causation?”

Austin Bradford Hill, “The Environment and Disease: Association or Causation?” 58 Proc. Royal Soc’y Med. 295, 295 (1965). Colditz, and plaintiff’s counsel, did not run away from the challenge; they embraced statistical significance and presented an argument for why the association was “clear-cut” (not created by bias or confounding).

In one of his lengthy, leading questions, plaintiffs’ counsel attempted to suggest that statistical significance, or a confidence interval that excluded a risk ratio of 1.0, excluded bias as well as chance. Colditz to his credit broke from the straight jacket of “yes, sirs,” and disagreed as to bias. Smith, perhaps chastised then took a chance and asked an open-ended question about what a confidence interval was. With the bit in his mouth, Colditz managed to describe the observed confidence interval incorrectly as providing the range within which the point estimate would fall 95% of the time if the same study were repeated many times! There is a distribution of 95% confidence intervals, which cover the true parameter 95% of the time, assuming a correct statistical model, random sampling, and no bias or confounding. For the observed confidence interval, the true value is either included or not. Perhaps Colditz was thinking of a prediction interval, but Smith had asked for a definition of a confidence interval, and the jury got non-sense.

Dose Response

Colditz parsed the remaining Bradford Hill factors, and opined that exposure-gradient or dose response was good to have but not necessary to support a causal conclusion. Colditz opined, with respect to whether the statistical assessment of a putative dose-response should include non-exposed women, that the non-exposed women should be excluded. This was one of the few technical issues that Dr. Huh engaged with, in the defense case, but Dr. Colditz was not confronted with any textbooks or writings that cast doubt on his preference for excluding non-users.

Plausibility

Plaintiff’s counsel spent a great deal of time, mostly reading lengthy passages of articles on this or that plausible mechanism for talc’s causing human ovarian cancer, only to have Colditz, with little or no demonstrated expertise in biological mechanism, say “yes.” Some articles discussed that talc use was a modifiable risk and that avoiding perineal talc use “may” reduce ovarian cancer risk. Smith would read (accurately) and then ask Colditz whether he agreed that avoiding talc use would reduce ovarian cancer in women. Colditz himself catches and corrects Smith, some times, but not others.

Smith read from an article that invokes a claim that asbestos (with definition as to what mineral) causes ovarian cancer. Colditz agreed. Smith testified that talc has asbestos in it, and Colditz agreed. Smith read from an article that stated vaguely that talc is chemically similar to asbestos and thus this creates plausibility for a causal connection between talc and cancer. Colditz agreed, without any suggestion that he understands whether or not talc is morphologically similar to asbestos. It seems unlikely that Colditz had any real expertise to offer here, but Smith could not resist touching all bases with Colditz; and the defense did not object or follow up on these excesses.

Smith and Colditz, well mostly Smith, testified that tubal ligation reduces the otherwise observed increased risk of ovarian cancer from talc use. Smith here entrusts Colditz with providing the common-sense explanation. There is no meaningful cross-examination on this “jury friendly” point.

Consistency

Colditz testifed that the studies, both case-control and cohort studies, were consistent in showing an increased risk of ovarian cancer in association with talc use. Indeed, the studies are mostly consistent; the issue is whether they are consistently biased or consistently showing the true population risk. The defense chose to confront Colditz with the lack of statistical significance in some studies (with elevated risk ratios) as though these studies were inconsistent with the studies that found similar risk ratios, with p-values less than 5%. This confrontation did not go well for the defense, either on cross-examination of Colditz, or on direct examination of Dr. Huh. Colditz backed up his opinion on consistency with the available meta-analyses, which find very low p-values for the summary estimate of risk ratio for talc use and ovarian cancer.

Unlike the Zoloft case1, in which consistency was generated across different end points by cherry picking, the consistency in the talc case was evidenced by a consistent elevation of risk ratios for the same end point, across studies. When subgroups of ovarian cell or tumor types were examined, statistical significance was sometimes lost, but the direction of the risk ratio above one was maintained. Meta-analyses generated summary point estimates with very low p-values.

The Gold Standard

Colditz further gilded the consistency lilly by claiming that the Terry study2, a pooled analysis of available case-control studies, was the “gold standard” in this area of observational epidemiology. Smith and Colditz presented at some length as to how the Cochrane Collaboration has labeled combined “individual patient data” (IPD) analyses as the gold standard. Colditz skimmed over the Cochrane’s endorsement of IPD analyses as having been made in the context of systematic reviews, involving primarily randomized clinical trials, for which IPD analyses allow time-to-event measurements, which can substantially modify observed risk ratios, and even reverse their direction. The case-control studies in the Terry pooled analysis did not have anything like the kind of prospectively collected individual patient data, which would warrant holding the Terry paper up as a “gold standard,” and Terry and her co-authors never made such a claim for their analysis. Colditz’s claim about the Terry study cried out for strong rebuttal, which never came.

The defense should have known that this hyperbolic testimony would be forthcoming, but they seemed not to have a rebuttal planned, other than dismissing case-controls studies generally as smaller than cohort studies. Rather than “getting into the weeds” about the merits of pooled analyses of observational studies, as opposed to clinical trials, the defense continued with its bizarre stance that the cohort studies were better because larger, while ignoring that they are smaller with respect to number of ovarian cancer cases and have less precision than the case-control studies. SeeNew Jersey Kemps Ovarian Cancer – Talc Cases” (Sept. 16, 2016). The defense also largely ignored Colditz’s testimony that exposure data collected in the available cohort studies was of limited value because lacking in details about frequency and intensity of use, and in some cases, collected on only one occasion.

Specific Causation

Colditz disclaimed the ability or intention to offer a specific causation opinion about Ms. Slemp’s ovarian cancer. Nonetheless, Colditz volunteered that “cancer is multifactorial,” which says very little because it says so much. In plaintiffs’ counsel’s hands, this characterization became a smokescreen to indict every possible present risk factor as playing a part in the actual causation of a particular case, such as Ms. Slemp’s case. No matter that the plaintiff was massively obese, and a smoker; every risk factor present must be, by fiat, in the “causal pie.”

But this would seem not to be Colditz’s own opinion. Graham Colditz has elsewhere asserted that an increased risk of disease cannot be translated into the “but-for” standard of causation3:

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.”

Just because a risk factor (assuming it is real and causal) is present does not put in the causal set.

Cross-Examination

The direct examination of Graham Colditz included scurrilous attacks on J & J’s lobbying, paying FDA user fees, and other corporate conduct, based upon documents of which Colditz had not personal knowledge. Colditz was reduced to nothing more than a backboard, off which plaintiff’s counsel could make his shots. On cross, the defense carefully dissected this direct examination and obtained disavowals from Colditz that he had suggested any untoward conduct by J & J. The jury could have been spared their valuable time by a trial judge who did not allow the scurrilous, collateral attacks in the first place.

The defense also tried to diminish Dr. Colditz’s testimony as an opinion coming from a non-physician. The problem, however, was that Colditz is a physician, who understands the biological issues, even if he is not a pathologist, toxicologist, or oncologist. Colditz did not offer opinions about Slemp’s medical treatment, and there was nothing in this line of cross-examination that lessened the impact of Colditz’s general causation testimony.

Generally, the cross-examination did not hurt Dr. Colditz’s strongly stated opinion that talc causes ovarian cancer. The defense (and plaintiff’s counsel before them) spent an inordinate amount of time on why Dr. Colditz has not updated his website to state publicly that talc causes ovarian cancer. Colditz blamed the “IT” guys, a rather disingenuous excuse. His explanation on direct, and on cross, as to why he could not post his opinion on his public-service website was so convoluted, however, that there was no clear admission or inference of dereliction. Colditz was permitted to bill his opinion, never posted to his institution’s website, as a “consensus opinion,” endorsed by several researchers, based upon hearsay emails and oral conversations.


1 See In re Zoloft Prod. Liab. Litig., No. 16-2247 , __ F.3d __, 2017 WL 2385279, 2017 U.S. App. LEXIS 9832 (3d Cir. June 2, 2017) (affirming exclusion of dodgy opinion, which involved changing subgroup end points across studies of maternal sertraline use and infant cardiac birth defects ).

2 Kathryn L. Terry, et al., “Genital powder use and risk of ovarian cancer: a pooled analysis of 8,525 cases and 9,859 controls,” 6 Cancer Prev. & Research 811 (2013).

3 Graham A. Colditz, “From epidemiology to cancer prevention: implications for the 21st Century,” 18 Cancer Causes Control 117, 118 (2007).

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