The Cochrane Library has withdrawn two reviews evaluating the effectiveness of diabetes treatments because some of the papers’ authors work with pharmaceutical companies.

Bianca Hemmingsen, first author on both reviews, told us the Cochrane Library asked the authors to remove the researchers with ties to pharma, but after one “refused to withdraw,” both papers were pulled entirely.

However, Hemmingsen insists that their employment had no impact on either paper.

This breaks the typical mold for Cochrane withdrawals, which are usually only pulled to indicate updates and show that older reviews no longer represent the best evidence.

“Targeting intensive glycaemic control versus targeting conventional glycaemic control for type 2 diabetes mellitus” was published in 2011 by researchers in Denmark who examined how intensive glycemic control compares to conventional methods. They found that intensive approaches had higher risks but no clear benefit.

According to the notice, the journal initially didn’t believe the authors’ employment “was a breach of the rules”:

The Cochrane Metabolic and Endocrine Disorders Group withdrew this review as of Issue 7, 2015 because the involvement of two authors (C Hemmingsen and SS Lund) being employed in pharmaceutical companies. The authors of the review and the Cochrane Metabolic and Endocrine Disorders Group did not find that this was a breach of the rules of the Cochrane Collaboration at the time when it was published. However, after the publication of the review, the Cochrane Collaboration requested withdrawal of the review due to the employment of the two authors. A new protocol for a review to cover this topic will be published. This will have a new title and a markedly improved protocol fulfilling new and important developments and standards within the Cochrane Collaboration as well as an improved inclusion and search strategy making it necessary to embark on a completely new review project.

It has been cited 18 times, according to Thomson Scientific’s Web of Knowledge.

Hemmingsen said that when her co-authors were asked to step down from the article, one refused:

When we conducted the Cochrane review, two of our co-authors were employed in the pharmaceutical industry. The Cochrane Collaboration decided after the publication that no authors could be employed in a pharmaceutical company. We were therefore contacted by the editor of the Cochrane Metabolic and Endocrine Disorders Group in order to update the review without the two authors employed in the pharmaceutical industry. One of the authors employed in a pharmaceutical industry refused to withdraw from the update, as he claimed there would be a large overlap with the existing review. It was therefore decided to withdraw the review.

She also said that the affiliation didn’t create any bias or have any impact on the review:

The remaining authors have at no point felt that the authors employed in the pharmaceutical companies have been biased during the review. Besides, the conclusion of the review is not in the interest of any pharmaceutical company. The conclusion is that there is no proven benefit of intensive glycaemic control, but the risks of serious adverse events and severe hypoglycaemia are increased.

In the review, second author, Søren S Lund, was listed at the Steno Diabetes Center in Denmark, but the updated affiliation on the withdrawal notice and Lund’s ResearchGate profile lists his affiliation as Boehringer Ingelheim, which sells diabetes treatments.

The second withdrawn review, “Sulphonylurea monotherapy for patients with type 2 diabetes mellitus” was also published in 2011 and authored by many of the same authors.

The paper examined the potential of sulfonylurea, the main ingredient in several antidiabetic drugs used to treat type 2 diabetes. Authors concluded that there was insufficient evidence to support the use of sulfonylurea monotherapy, and a need for “large-scale and long-term randomised clinical trials,” according to the abstract.

Cochrane published a similar withdrawal notice:

The Cochrane Metabolic and Endocrine Disorders Group withdrew this review as of Issue 7, 2015 because of the involvement of one author (SS Lund) being employed in a pharmaceutical company. The authors of the review and the Cochrane Metabolic and Endocrine Disorders Group did not find that this was a breach of the rules of the Cochrane Collaboration at the time when it was published. However, after the publication of the review, the Cochrane Collaboration requested withdrawal of the review due to the employment of the author. A new protocol for a review to cover this topic will be published. This will have a new title and a markedly improved protocol fulfilling new and important developments and standards within the Cochrane Collaboration as well as an improved inclusion and search strategy making it necessary to embark on a completely new review project.

Hemmingson said that Lund had also refused to withdraw from this paper. She also noted that remaining authors didn’t feel that the review had been biased.

The remaining authors have at no point felt that Dr Lund has been biased during the sulphonylurea review. Dr Lund stated that he would refuse to withdraw as an author if we performed an update of the sulphonylurea review.

It has been cited 17 times, according to Thomson Scientific’s Web of Knowledge.

A spokesperson for Cochrane declined to comment further on the withdrawals.

We’ve contacted Lund for a statement. We’ll update with any reply.

Hat tip: Tom Finucane

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