Did Undisclosed Conflict Delay Publication of Denture Cream Study?

Fran Lowry

February 17, 2011

February 17, 2011 — A study suggesting neurologic damage from overuse of denture cream was delayed for 2 years by a reviewer with undisclosed conflicts of interest charges a news report televised February 8 on ABC's World News Tonight with Diane Sawyer.

But the lead author of the study, published in the American Academy of Neurology (AAN) journal Neurology in 2008, has told Medscape Medical News that she saw nothing wrong with the peer review process that assessed her research.

In fact, says Sharon Nations, MD, associate professor of neurology at the University of Texas Southwestern Medical Center in Dallas, the suggestions made by all 3 reviewers were excellent and led her and her team to improve the paper.

The peer review did not lead to a delay in publication, as alleged by ABC News, she maintains.

The reviewer in question, Kenneth Shay, DDS, a dentist who practices in Ann Arbor, Michigan, admits that he was wrong not to disclose that he had a conflict of interest with regard to Procter & Gamble but assumed that the journal had gotten his name from the company's site.

He also admits to sending the manuscript to someone at the company to "double-check" his facts, an action that he now calls a "big mistake."

That being said, Dr. Shay insists that he gave a fair and unbiased review of the study and sent his suggestions for revision in a timely manner.

"I did not comment on the paper as a Procter and Gamble employee. I came at it as somebody who knows a lot about denture adhesives," he told Medscape Medical News.

Link to Nerve Damage

The report, by ABC News' 20/20 anchor Chris Cuomo, chief of the Law and Justice Unit, also appeared online in print under the title "Fixodent: Can Excessive Use of Popular Denture Cream Cause Nerve Damage?" authored by Lauren Pearle, James Hill, Chris Vlasto, and Cleopatra Andreadis.

The ABC journalists say that the connection between Fixodent and neurologic damage was made 5 years ago and quote Dr. Nations as saying, "They had high zinc levels that we could measure in the blood....And all of them reported that they were using very large amounts of denture cream."

The journalists go on to write, "It [Dr. Nation's study] was delayed, according to its authors, because of a peer review by Dr. Kenneth Shay, a dentist, who lambasted the study and called the link between excessive use of denture cream and neurologic disease 'little more than speculation.'"

The study, which was first submitted in late 2006, was eventually published in Neurology as an e-Pub ahead of print on June 4, 2008 (Neurology. 2008;71:639-643).

Dr Nations said she only found out about the ABC report after a colleague emailed her to tell her she was on the news.

"No one from ABC News, no one from the show, spoke with me or Dr. Wolfe or Dr. Trivedi (G.I. Wolfe and J.R. Trivedi, 2 other coauthors of the study)," she said in a telephone interview.

According to ABC, Dr. Shay was a paid consultant to Procter & Gamble, the manufacturers of Fixodent, and he failed to disclose this when he reviewed Dr. Nation's study.

"I can't speak to what he did or what evidence they had or who he might have had communications with. I know nothing about that," Dr. Nations said. "All I know is we got the reviews, we modified our answers, and a lot of the advice was very helpful. I think it made it a better paper because it helped us to explain things better. We addressed all the reviewers' advice, comments, and questions, and then we sent the article back to Neurology and they published it."

She added that as far as she and her authors are concerned, the peer review process was working as it should. "Criticisms are part of the peer review process. I welcomed them because we wanted the paper to be as complete and as accurate as possible," Dr. Nations said.

The paper took a long time to be published because of logistic and personal reasons, she added. "It's just standard procedure. There was a delay from the time we got the reviewers' comments until the time we sent it back...and this had nothing to do with the journal or Dr. Shay because we don't know who the comments are from; they are anonymous. We responded to them, but the manuscript came back to us at a time that was logistically — because of a lot of work and personal commitments — difficult for us, and we had limited time to work on the return. That's what delayed getting it published."

I don't remember the specific time frame between the time it was accepted and the time that it appeared in the journal, but it was a standard length of time. It didn't have anything to do with Dr. Shay or any of the reviewers. There was nothing strange about this paper not being published right away.

Normally, there is also some delay from the time a paper is accepted with revisions until it is published, Dr. Nations said.

"I don't remember the specific time frame between the time it was accepted and the time that it appeared in the journal, but it was a standard length of time. It can take longer to get these things done. It didn't have anything to do with Dr. Shay or any of the reviewers," she said. "There was nothing strange about this paper not being published right away."

Neurology Comments

Robert A. Gross, MD, PhD, the editor-in-chief of Neurology, was unavailable to comment on the ABC News report. But in a statement conveyed by the AAN's press office, Dr. Gross condemned Dr. Shay's actions.

"Dr. Shay did not disclose any conflict of interest to the editor-in-chief of Neurology," he writes. "Furthermore, it appears that Dr. Shay improperly shared the manuscript authored by Dr. Sharon Nations to Procter and Gamble, in violation of the journal's confidentiality policy."

Dr. Gross added that much of the delay in publication was the result of the time it took the authors to resubmit their revision, which accords with Dr. Nation's account. "The editorial office's review procedure was in line with standard time frames,” the statement notes.

Neurology considers violations of our ethics policies to be egregious misconduct, and the academy's general counsel is reviewing its options with the editors.

"Neurology considers violations of our ethics policies to be egregious misconduct, and the academy's general counsel is reviewing its options with the editors," Dr. Gross adds. "Furthermore, we will continue our ongoing review of policies for authors and reviewers to ensure that the integrity of Neurology is preserved for our readers and the patients and caregivers affected by the research we publish."

Dr. Gross referred readers to a recent editorial outline that "outlines the value and limitations of any disclosure policy" of Neurology and to a second document that provides guidelines for reviewers "that stress full disclosure and confidentiality as central to the review process."

Finally, Dr. Gross invited Neurology readers to give their feedback at journal@neurology.org.

Dr. Shay Replies

In an interview with Medscape Medical News, Dr. Shay admitted that he was wrong not to disclose that he had a conflict of interest with regard to Procter & Gamble but said that it did not seem relevant at the time he was approached to peer review Dr. Nation's study.

"I'm a dentist. Out of the blue I get an invitation from a journal that I've never heard of to review a paper about denture adhesives. I assumed they found me because of an article I had written about denture adhesives, which was on the Procter and Gamble Website. I figured the boiler plate that asked about conflicts of interest didn't apply to me because obviously they needed somebody who was an authority on denture adhesives, or they wouldn't have asked me," he recalled.

Dr. Shay, who specializes in geriatric dentistry, became interested in learning more about denture adhesives in the late 1980s and ended up writing a paper on the subject for the Journal of the American Dental Association. Soon after, he was approached by Procter & Gamble to be on its denture advisory board.

"So, no, I did not explicitly say I had an affiliation with Procter and Gamble. I should have. I absolutely should have. But I didn't, and my rationale at the time was it was just so patently obvious how they got my name," he said.

So, no, I did not explicitly say I had an affiliation with Procter and Gamble....I absolutely should have. But I didn't, and my rationale at the time was it was just so patently obvious how they got my name.

Dr. Shay said he asked the study authors to tone down their initial recommendation that all users of denture cream containing zinc should have their blood zinc levels checked. "That's like saying anybody who salts their food should get their sodium levels checked. I felt this recommendation was way over the top."

He also asked the study authors to look more closely at how the amount of zinc that was used by the 4 subjects in the study compared with the amount of zinc that is normally used by most people.

"The 4 cases they reported on were aberrations," he says. "Some of those subjects were eating the product in addition to applying it to their dentures at about 30 times the rate you're supposed to. These people were in their 30s and 40s and had been wearing dentures for 20 years. They were way outside the bell-shape curve on a lot of things. and I felt that should be addressed in the study. I felt that the authors should emphasize more that these people were not using this product the way it was supposed to be used," he said.

Dr. Shay says the authors ignored his initial suggestions for revision. Before sending the same suggestions again, however, he sent the unpublished manuscript to someone he knew at Procter and Gamble to "double check" his facts.

"Big mistake. I knew it. In the cover note I said 'please don't share this, I shouldn't be doing this,' but I just wanted to make sure that I wasn't barking up the wrong tree with my facts," he said.

"I never heard back from the Procter people," he added.

Eventually, all of his criticisms were answered and the article was published.

Dr. Shay, who is no longer a paid consultant for Procter & Gamble, admits that from the point of view of the network news, which he called a "a 1-dimensional, 15-second spot," he is guilty of everything that was said.

"But I didn't get paid for doing that review. I was doing a favor for this journal I'd never even heard of and this is what happens. I think when the news is slightly titillating, as it was in this case, the details don't matter. It's the titillation that matters."

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