Fixodent Study Causes Lockjaw in Plaintiffs’ Counsel

Litigation Drives Science

Back in 2011, the Fixodent MDL Court sustained Rule 702 challenges to plaintiffs’ expert witnesses. “Hypotheses are verified by testing, not by submitting them to lay juries for a vote.” In re Denture Cream Prods. Liab. Litig., 795 F. Supp. 2d 1345, 1367 (S.D.Fla.2011), aff’d, Chapman v. Procter & Gamble Distrib., LLC, 766 F.3d 1296 (11th Cir. 2014). The Court found that the plaintiffs had raised a superficially plausible hypothesis, but that they had not verified the hypothesis by appropriate testing[1].

Like dentures to Fixodent, the plaintiffs stuck to their claims, and set out to create the missing evidence. Plaintiffs’ counsel contracted with Dr. Salim Shah and his companies Sarfez Pharmaceuticals, Inc. and Sarfez USA, Inc. (“Sarfez”) to conduct human research in India, to support their claims that zinc in denture cream causes neurological damage[2]In re Denture Cream Prods. Liab. Litig., Misc. Action 13-384 (RBW), 2013 U.S. Dist. LEXIS 93456, *2 (D.D.C. July 3, 2013).  When the defense learned of this study, and the plaintiffs’ counsel’s payments of over $300,000, to support the study, they sought discovery of raw data, study protocol, statistical analyses, and other materials from plaintiffs’ counsel.  Plaintiffs’ counsel protested that they did not have all the materials, and directed defense counsel to Sarfez.  Although other courts have made counsel produce similar materials from the scientists and independent contractors they engaged, in this case, defense counsel followed the trail of documents to contractor, Sarfez, with subpoenas in hand.  Id. at *3-4.

The defense served a Rule 45 subpoena on Sarfez, which produced some, but not all responsive documents. Proctor & Gamble pressed for the missing materials, including study protocols, analytical reports, and raw data.  Id. at *12-13.  Judge Reggie Walton upheld the subpoena, which sought underlying data and non-privileged correspondence, to be within the scope of Rules 26(b) and 45, and not unduly burdensome. Id. at *9-10, *20. Sarfez attempted to argue that the requested materials, listed as email attachments, might not exist, but Judge Walton branded the suggestion “disingenuous.”  Attachments to emails should be produced along with the emails.  Id. at *12 (citing and collecting cases). Although Judge Walton did not grant a request for forensic recovery of hard-drive data or for sanctions, His Honor warned Sarfez that it might be required to bear the cost of forensic data recovery if it did not comply the court’s order.  Id. at *15, *22.

Plaintiffs Put Their Study Into Play

The study at issue in the subpoena was designed by Frederick K. Askari, M.D., Ph.D., an associate professor of hepatology, in the University of Michigan Health System. In re Denture Cream Prods. Liab. Litig., No. 09–2051–MD, 2015 WL 392021, at *7 (S.D. Fla. Jan. 28, 2015). At the instruction of plaintiffs’ counsel, Dr. Askari sought to study the short-term effects of Fixodent on copper absorption in humans. Working in India, Askari conducted the study on 24 participants, who were given a controlled diet for 36 days. Of the 24 participants, 12, randomly selected, received 12 grams of Fixodent per day (containing 204 mg. of zinc). Another six participants, randomly selected, were given zinc acetate, three times per day (150 mg of zinc), and the remaining six participants received placebo, three times per day.

A study protocol was approved by an independent group[3], id. at *9, and the study was supposed to be conducted with a double blind. Id. at *7. Not surprisingly, those participants who received doses of Fixodent or zinc acetate had higher urinary levels of zinc (pee < 0.05). The important issue, however, was whether the dietary zinc levels affect copper excretion in a way that would support plaintiffs’ claims that copper levels were lowered sufficiently by Fixodent to cause a syndromic neurological disorder. The MDL Court ultimately concluded that plaintiffs’ expert witnesses’ opinions on general causation claims were not sufficiently supported to satisfy the requirements of Rule 702, and upheld defense challenges to those expert witnesses. In doing so, the MDL Court had much of interest to say about case reports, weight of the evidence, and other important issues. This post, however, concentrates on the deviations of one study, commissioned by plaintiffs’ counsel, from the scientific standard of care. The Askari “research” makes for a fascinating case study of how not to conduct a study in a litigation caldron.

Non-Standard Deviations

The First Deviation – Changing the Ascertainment Period After the Data Are Collected

The protocol apparently identified a primary endpoint to be:

“the mean increase in [copper 65] excretion in fecal matter above the baseline (mg/day) averaged over the study period … to test the hypothesis that the release of [zinc] either from Fixodent or Zinc Acetate impairs [copper 65] absorption as measured in feces.”

The study outcome, on the primary end point, was clear. The plaintiffs’ testifying statistician, Hongkun Wang, stated in her deposition that the fecal copper (whether isotope Cu63 or Cu65) was not different across the three groups (Fixodent, zinc acetate, and placebo). Id. at *9[4]. Even Dr. Askari himself admitted that the total fecal copper levels were not increased in the Fixodent group compared with the placebo control group. Id. at *9.[5]

Apparently after obtaining the data, and finding no difference in the pre-specified end point of average fecal copper levels between Fixodent and placebo groups, Askari turned to a new end point, measured in a different way, not described in the protocol as the primary end point.

The Second Deviation – Changing Primary End Point After the Data Are Collected

In the early (days 3, 4, and 5) and late (days 31, 32, and 33) part of the Study, participants received a dose of purified copper 65[6] to help detect the “blockade of copper.” Id. at 8*. The participants’ fecal copper 65 levels were compared to their naturally occurring copper 63 levels. According to Dr. Askari:

“if copper is being blocked in the Fixodent and zinc acetate test subjects from exposure to the zinc in the test product (Fixodent) and positive control (zinc acetate), the ratio of their fecal output of copper 65 as compared to their fecal output of copper 63 would increase relative to the control subjects, who were not dosed with zinc. In short, a higher ratio of copper 65 to copper 63 reflects blocking of copper.”


Askari analyzed the ratio of two copper isotopes (Cu65 /Cu63), in the limited period of observation to study days 31 to 33. Id. at *9. Askari thus changed the outcome to be measured, the timing of the measurement, and manner of measurement (average over entire period versus amount on days 31 to 33). On this post hoc, non-prespecified end point, Askari claimed to have found “significant” differences.

The MDL Court expressed its skepticism and concern over the difference between the protocol’s specified end point, and one that came into the study only after the data were obtained and analyzed. The plaintiffs claimed that it was their (and Askari’s) intention from the initial stages of designing the Fixodent Blockade Study to use the Cu65/Cu63 ratio as the primary end point. According to the plaintiffs, the isotope ratio was simply better articulated and “clarified” as the primary end point in the final report than it was in the protocol. The Court was not amused or assuaged by the plaintiffs’ assurances. The study sponsor, Dr. Salim Shah could not point to a draft protocol that indicated the isotope ratio as the end point; nor could Dr. Shah identify a request for this analysis by Wang until after the study was concluded. Id. at *9.[7]

Ultimately, the Court declared that whether the protocol was changed post hoc after the primary end point provided disappointing analysis, or the isotope ratio was carelessly omitted from the protocol, the design or conduct of the study was “incompatible with reliable scientific methodology.”

The Third Deviation – Changing the Standard of “Significance” After the Data Are Collected and P-Values Are Computed

The protocol for the Blockade study called for a pre-determined Type I error rate (p-value) of no more than 5 percent.[8] Id. at *10. The difference in the isotope ratio showed an attained level of significance probability of 5.7 percent, and thus even the post hoc end point missed the prespecified level of significance. The final protocol changed the value of “significance” to 10 percent, to permit the plaintiffs to declare a “statistically significant” result. Dr. Wang admitted in deposition that she doubled the acceptable level of Type I error only after she obtained the data and calculated the p-value of 0.057. Id. at *10.[9]

The Court found that this deliberate moving of the statistical goal post reflected a “lack of objectivity and reliability,” which smacked of contrivance[10].

The Court found that the study’s deviations from the protocol demonstrated a lack of objectivity. The inadequacy of the Study’s statistical analysis plan supported the Court’s conclusion that Dr. Askari’s supposed finding of a “statistically significant” difference in fecal copper isotope ratio between Fixodent and placebo group participants was “not based on sufficiently reliable and objective scientific methodology” and thus could not support plaintiffs’ expert witnesses’ general causation claims.

The Fourth Deviation – Failing to Take Steps to Preserve the Blind

The protocol called for a double-blinded study, with neither the participants nor the clinical investigators knowing which participant was in which group. Rather than delivering the three different groups capsules that looked similar, the group each received starkly different looking capsules. Id. at *11. The capsules for one set were apparently so large that the investigators worried whether the participants would comply with the dosing regimen.

The Fifth Deviation – Failing to Take Steps to Keep Biological Samples From Becoming Contaminated

Documents and emails from Dr. Shah acknowledged that there had been “difficulties in storing samples at appropriate temperature.” Id. at *11. Fecal samples were “exposed to unfrozen and undesirable temperature conditions.” Dr. Shah called for remedial steps from the Study manager, but there was no documentation that such steps were taken to correct the problem. Id.

The Consequences of Discrediting the Study

Dr. Askari opined that the Study, along with other evidence, shows that Fixodent can cause copper deficiency myeloneuropathy (“CDM”). The plaintiffs, of course, argued that the Defendants’ criticisms of the Fixodent

Study’s methodology went merely to the “weight rather than admissibility.” Id. at *9. Askari’s study was but one leg of the stool, but the defense’s thorough discrediting of the study was an important step in collapsing the support for the plaintiffs’ claims. As the MDL Court explained:

“The Court cannot turn a blind eye to the myriad, serious methodological flaws in the Fixodent Blockade Study and conclude they go to weight rather than admissibility. While some of these flaws, on their own, may not be serious enough to justify exclusion of the Fixodent Blockade Study; taken together, the Court finds Fixodent Blockade Study is not “good science,” and is not admissible. Daubert, 509 U.S. at 593 (internal quotation marks and citation omitted).”

Id. at *11.

A study, such as the Fixodent Blockade Study, is not itself admissible, but the deconstruction of the study upon which plaintiffs’ expert witnesses relied, led directly to the Court’s decision to exclude those witnesses. The Court omitted any reference to Federal Rule of Evidence 703, which addresses the requirements of facts and data, otherwise inadmissible, which may be relied upon by expert witnesses in reaching their opinions.


[1] SeePhiladelphia Plaintiff’s Claims Against Fixodent Prove Toothless” (May 2, 2012); Jacoby v. Rite Aid Corp., 2012 Phila. Ct. Com. Pl. LEXIS 208 (2012), aff’d, 93 A.3d 503 (Pa. Super. 2013); “Pennsylvania Superior Court Takes The Bite Out of Fixodent Claims” (Dec. 12, 2013).

[2] SeeUsing the Rule 45 Subpoena to Obtain Research Data” (July 24, 2013)

[3] The group was identified as the Ethica Norma Ethical Committee.

[4] citing Wang Dep. at 56:7–25, Aug. 13, 2013), and Wang Analysis of Fixodent Blockade Study [ECF No. 2197–56] (noting “no clear treatment effect on Cu63 or Cu65”).

[5] Askari Dep. at 69:21–24, June 20, 2013.

[6] Copper 65 is not a typical tracer; it is not radioactive. Naturally occurring copper consists almost exclusively of two stable (non-radioactive) isotope, Cu65 about 31 percent, Cu63 about 69 percent. See, e.g., Manuel Olivares, Bo Lönnerdal, Steve A Abrams, Fernando Pizarro, and Ricardo Uauy, “Age and copper intake do not affect copper absorption, measured with the use of 65Cu as a tracer, in young infants,” 76 Am. J. Clin. Nutr. 641 (2002); T.D. Lyon, et al., “Use of a stable copper isotope (65Cu) in the differential diagnosis of Wilson’s disease,” 88 Clin. Sci. 727 (1995).

[7] Shah Dep. at 87:12–25; 476:2–536:12, 138:6–142:12, June 5, 2013).

[8] The reported decision leaves unclear how the analysis would proceed, whether by ANOVA for the three groups, or t-tests, and whether there was multiple testing.

[9] Wang Dep. at 151:13–152:7; 153:15–18.

[10] 2015 WL 392021, at *10, citing Perry v. United States, 755 F.2d 888, 892 (11th Cir. 1985) (“A scientist who has a formed opinion as to the answer he is going to find before he even begins his research may be less objective than he needs to be in order to produce reliable scientific results.”); Rink v. Cheminova, Inc., 400 F.3d 1286, 1293 n. 7 (11th Cir.2005) (“In evaluating the reliability of an expert’s method … a district court may properly consider whether the expert’s methodology has been contrived to reach a particular result.” (alteration added)).


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