Why the Cochrane Collaboration needs to clean up conflicts of interest

  • A recent failure to correct a systematic review and meta-analysis demonstrates that Cochrane’s problem with conflict of interest is multilayered.
  • Cochrane  enlists thousands of volunteers committed to the evaluation of evidence independent of the interests of the investigators who conducted trials.
  • Cochrane is vigilant in requiring declaration of conflicts of interest but is inconsistent in policing their influence on reviews.
  • The Cochrane  has a mess to clean up.

ioannidisA recent interview of John Ioannidis by Retraction Watch expressed concern about Cochrane’s tainting by conflict of interest:

RW: You’re worried that Cochrane Collaboration reviews — the apex of evidence-based medicine — “may cause harm by giving credibility to biased studies of vested interests through otherwise respected systematic reviews.” Why, and what’s the alternative?

JI: A systematic review that combines biased pieces of evidence may unfortunately give another seal of authority to that biased evidence. Systematic reviews may sometimes be most helpful if, instead of focusing on the summary of the evidence, highlight the biases that are involved and what needs to be done to remedy the state-of-the-evidence in the given field. This often requires a bird’s eye view where hundreds and thousands of systematic reviews and meta-analyses are examined, because then the patterns of bias are much easier to discern as they apply across diverse topics in the same or multiple disciplines. Much of the time, the solution is that, instead of waiting to piece together fragments of biased evidence retrospectively after the fact, one needs to act pre-emptively and make sure that the evidence to be produced will be clinically meaningful and unbiased, to the extent possible. Meta-analyses should become primary research, where studies are designed with the explicit anticipation that they are part of an overarching planned cumulative meta-analysis.

The key points were (1) Retraction Watch is raising with John Ioannidis the concern that evidence-based medicine has been hijacked by special interest; (2) RW is specifically asking about the harm caused by the Cochrane Collaboration in lending undue credibility to studies biased by vested interest; and (3) Ioannidis replies that instead of focusing on summarizing the evidence, Cochrane should highlight biases and point to what needs to be done to produce trustworthy, clinically meaningful and unbiased assessment.

A recent exchange of comments about a systematic review and meta-analysis demonstrates the problem.

Larun L, Brurberg KG, Odgaard-Jensen J, Price JR. Exercise therapy for chronic fatigue syndrome. Cochrane Database Syst Rev. 2016; CD003200.

cochraneThe systematic review is behind a paywall. That is particularly unfortunate because persons providing systematic reviews undergo extensive training and then work for free. The fruits of their labor identifying would best be evidence should be available around the world, for free. But to see their work, one has to either go through a University library or pay a fee to the for-profit Wiley.

An abridged version of the review is available here:

Larun L, Odgaard-Jensen J, Price JR, Brurberg KG. An abridged version of the Cochrane review of exercise therapy for chronic fatigue syndrome. European Journal of Physical and Rehabilitation Medicine. 2015 Sep.

To get around the pay wall of the full review, the commentator, Tom Kindlon cleverly reposted his comment at PubMed Commons where everybody can access it for free:

In his usual polite style, Mr Kindlon opens with an expression thanks the authors of the systematic review and closes with a thanks for their reading his comments. In between, he makes a number of interesting points before getting to the following:

“Selective reporting (outcome bias)” and White et al. (2011)

I don’t believe that White et al. (2011) (the PACE Trial) (3) should be classed as having a low risk of bias under “Selective reporting (outcome bias)” (Figure 2, page 15). According to the Cochrane Collaboration’s tool for assessing risk of bias (21), the category of low risk of bias is for: “The study protocol is available and all of the study’s pre-specified (primary and secondary) outcomes that are of interest in the review have been reported in the pre-specified way”. This is not the case in the PACE Trial. The three primary efficacy outcomes can be seen in the published protocol (22). None have been reported in the pre-specified way. The Cochrane Collaboration’s tool for assessing risk of bias states that a “high risk” of bias applies if any one of several criteria are met, including that “not all of the study’s pre-specified primary outcomes have been reported” or “one or more primary outcomes is reported using measurements, analysis methods or subsets of the data (e.g. subscales) that were not pre-specified”. In the PACE Trial, the third primary outcome measure (the number of “overall improvers”) was never published. Also, the other two primary outcome measures were reported using analysis methods that were not pre-specified (including switching from the bimodal to the Likert scoring method for The Chalder Fatigue Scale, one of the primary outcomes in your review). These facts mean that the “high risk of bias” category should apply.

I’m sure John Ioannidis would be pleased with Kindlon raising this point.

In order to see the response from the author of the systematic review one has to get behind the paywall. If you do that, you can see that Lillebeth Larun reciprocates Kindlon’s politeness, agrees that some of his points should be reflected in future research, but takes issue with a key one. I haven’t asked him, but I don’t think John Ioannidis is would be happy with her response:

Selective reporting (outcome bias)

The Cochrane Risk of Bias tool enables the review authors to be transparent about their judgments, but due to the subjective nature of the process it does not guarantee an indisputable consensus. You particularly mention the risk of bias in the PACE trial regarding not providing pre-specified outcomes however the trial did pre-specify the analysis of outcomes. The primary outcomes were the same as in the original protocol, although the scoring method of one was changed and the analysis of assessing efficacy also changed from the original protocol. These changes were made as part of the detailed statistical analysis plan (itself published in full), which had been promised in the original protocol. These changes were drawn up before the analysis commenced and before examining any outcome data. In other words they were pre-specified, so it is hard to understand how the changes contributed to any potential bias. The relevant paper also alerted readers to all these changes and gave the reasons for them. Overall, we don’t think that the issues you raise with regard to the risk of selective outcome bias are such as to suspect high risk of bias, but recognize that you may reach different conclusions than us.

aaaarghI strongly take issue and see conflicts of interest rearing their ugly heads at a number of points.

  1. One can’t dismiss application of the Cochrane Risk of Bias tool as simply being subjective and then say whatever you want to say. The tool has well-specified criteria, and persons completing a review have to be trained to consensus. One of the key reasons that a single author can’t conduct a proper Cochrane collaboration review is that requires a trained team to agree on ratings of risk of bias. That’s one of the many checks and balances built into a systematic review.

Fortunately,  Cochrane  provides an important free chapter as a guide. Lots of people who conduct systematic reviews and meta-analyses who are not members of  Cochrane  nonetheless depend on the materials that the collaboration has developed because they are so clear, authoritative, and transparent in terms of the process by which they were developed.

  1. Largely as a result of our agitation,*applying the sixth of six risk of bias items (other bias) assesses whether the investigators a particular trial have a conflict of interest. The authors of the trial in question had a strong conflict of interest including paid and volunteer working for an insurance company and as assessors of disability eligibility. Ioannidis is would undoubtedly consider this as a high risk of bias.
  1. Larun dismisses the risk of bias associated with the investigators not sticking to the primary outcomes in their original protocol. She suggested deviations from these outcomes were specified before analyses commenced. However, this was an unblinded trial and the investigators could inspect incoming data. In fact, they actually sent out a newsletter to participants giving testimonials about the benefits of the trial while they were still recruiting patients. Think of it: if someone with ties to the pharmaceutical industry could peek at incoming data and make changes to designate outcomes, wouldn’t that be a high risk of bias? Of course.
  1. But it gets worse. Larun is a co-author with the investigators of the trial on another Cochrane protocol.

Larun L, Odgaard-Jensen J, Brurberg KG, Chalder T, Dybwad M, Moss-Morris RE, Sharpe M, Wallman K, Wearden A, White PD, Glasziou PP.  Exercise therapy for chronic fatigue syndrome (individual patient data) (Protocol).  Cochrane Database of Systematic Reviews 2014, Issue 4. Art. No.: CD011040.

  1. And one of the authors of the systematic review under discussion is a colleague in the department of the trial investigators.

How does Cochrane  define conflict of interest?

I’m a member of Cochrane and so I I am required to complete a yearly assessment of potential conflicts of interest. My report is kept on by the collaboration but not necessarily directly available to the public. You can download a PDF of the evaluation and an explanation here 

As you can see, Cochrane  staff and reviewers need to disclose (1) the financing of their review; (2) relevant financial activities outside the submitted work; (3) intellectual property such as patents, copyrights, and royalties; and (4) other relationships which has the instructions:

Use this section to report other relationships or activities that readers could perceive to have influenced, or that give the appearance of potentially influencing, what you wrote in the submitted work.

The conflicts of interest of Lillebeth Larun

A co-author of Lillebeth Larun on the systematic review under discussion is a colleague in the department of the investigators whose trial is being evaluated. Larun is a co-author on another protocol with these investigators. Examination of the acknowledgments that protocol indicates that the investigators provided both data and funding for meetings:

The author team held three meetings in 2011, 2012 and 2013 which were funded as follows:

  • 2011 via  Paul Glasziou, NIHR senior research fellow fund, Oxford Department of primary care.
  • 2012 via Hege R Eriksen, Uni Research Health, Bergen.
  • 2013 via Peter D White’s academic fund (Professor of Psychological Medicine, Centre for Psychiatry, Wolfson Institute of Preventive Medicine, Barts and The London School of Medicine and Dentistry, Queen Mary University of London).

So, the both the systematic review under discussion and the other protocol were conducted among “families and friends”. In dismissing concerns about risk of bias for a particular trial, Lillebeth Larun is ignoring the obvious strong bias for her associates.

She has no business conducting this review nor dismissing the high risk of bias of inclusion of their study.

So, what is going on here?

Peter White and the PACE investigator team are attempting to break down the checks and balances that a systematic review imposes on interpretation of results of clinical trials. That interpretation should be independent of the investigators who generated a trial and take into account their conflicts of interest. The PACE investigators had a conflict of interest when they generate the data and now they want to control the interpretation so that comes out in favor of their interest.

Some PACE investigators have ties to the insurance companies and they want the results to fit with the needs of these companies. Keep in mind that the insurance companies don’t necessarily care whether treatments work. Their intent is to require participation in treatment as a condition for receiving disability payments and to exclude disabled persons who want to treatment.

Cochrane collaboration takes conflict of interest seriously

A statement by the two editors heading the Cochrane Bone, Joint, and Muscle Trauma Group is quite quotable about the threats of involvement of investigators of the original trials to the integrity of systematic reviews.

Handoll H, Hanchard N. From observation to evidence of effectiveness: the haphazard route to finding out if a new intervention works. Cochrane Database of Systematic Reviews. 2014 Jan 1.

They state:

We feel should become a cardinal rule: the need to separate the clinical evaluation of innovations from their innovators, who irrespective of any of their endeavours to be ‘neutral’ have a substantial investment, whether emotional, perhaps financial, or in terms of professional or international status, in the successful implementation of their idea.

Disclosure of conflicts of interest may be insufficient to mitigate the effects:

The reporting of financial conflicts of interest in systematic reviews may not be sufficient to mitigate the effects of industry affiliations, and further measures may be necessary to ensure that industry collaborations do not compromise the scientific evidence.

Although these editors are concerned about pharmaceutical companies, their comments apply equally to other conflicts. In the case of the systematic review, the investigators of the original trial have financial conflicts and collaborations with the spokeswoman/first author of the systematic review under discussion. She has additional conflicts associated with their co-authoring and funding of another systematic review protocol.

I believe that if Cochrane  is intent on restoring its credibility, not only do they need to clean up this mess of layered conflicts of interest, they should investigate how it came about and how it can be avoided in the future.

I’ve already written to the collaboration and I await the response.



*Our article in The BMJ that won the Bill Silverman award specifically recommended:

…That the Cochrane Collaboration reconsider its position that trial funding and trial author-industry financial ties not be included in the risk of bias assessment. The 2008 version of the Cochrane handbook listed “inappropriate influence of funders” (section (for example, data owned by industry sponsor) as a potential source of bias that review authors could optionally incorporate in the “other sources of bias” domain of the Cochrane risk of bias tool.37 The 2011 version of the handbook, however, argues that “vested interests” should not be included in the risk of bias assessment, which “should be used to assess specific aspects of methodology that might be been influenced by vested interests and which may lead directly to a risk of bias” (section As previously noted,22 empirical criteria are generally used to select items (for example, sequence generation, blinding) that are included in assessments of risk of bias,38 48 including evidence of a mechanism, direction, and likely magnitude of bias. Empirical data show that trial funding by pharmaceutical companies and trial author-industry financial ties are associated with a bias towards positive results even when controlling for other study characteristics6 8 49 50 and, thus, meet these criteria. One concern might be that including conflicts of interest from included trials in the risk of bias assessment could result in “double counting” of potential sources of bias. However, ratings in the risk of bias table are not summed to a single score, and inclusion of risk of bias from conflicts of interest could reflect mechanisms through which industry involvement can influence study outcomes6 that are not fully captured by the current domains of the risk of bias tool (random sequence generation, allocation concealment, blinding of participants and staff, blinding of outcome assessment, incomplete outcome data, selective reporting, and other sources of bias). Furthermore, even if all relevant mechanisms were to be assessed, the degree of their influence may not be fully captured when reviewers only have access to the relatively brief descriptions of trial methods that are provided in most published reports. Inclusion of conflicts of interest from included trials in the risk of bias assessment would encourage a transparent assessment of whether industry funded trials and independently conducted trials reach similar conclusions. It would also make it explicit when an entire area of research has been funded by industry and would benefit from outside scrutiny.

8 thoughts on “Why the Cochrane Collaboration needs to clean up conflicts of interest

  1. It’s interesting that, as a patient, simply knowing some others with scientific backgrounds who share my skepticism in the validity of the PACE analysis, is sufficient for QMUL to label my application for a very small set of data from PACE as vexatious, and part of a campaign to overload them with work (I asked for the 32 data points plotted on a small but important graph, but not shown in a table). Yet, for them, being paid by insurance companies with a vested interest in the results, telling patients part-way through a trial how successful their treatment is considered to be, and having associates and working colleagues evaluate your work are not seen as even slightly suspicious. Sadly, I fear my comment here will add to their file on me.


  2. The recent Cochrane review “Exercise therapy for chronic fatigue syndrome” was done by the Cochrane Common Mental Disorders Group, which is coordinated by the Centre for Academic Mental Health in Bristol.

    The Cochrane Common Mental Disorders Group lists chronic fatigue syndrome under major conditions of interest.

    I wonder if this group has significant interests in chronic fatigue syndrome being seen as mental disorder. It is not possible to prove that chronic fatigue syndrome is a mental disorder, but the next best thing would be to show that psychotherapy is an effective treatment.

    The aforementioned review concluded that “… no evidence suggests that exercise therapy may worsen outcomes.” Yet I can cite a study (1) where the CBT and GET group had worse physical function and pain scores than the control group.

    A pattern in CBT and GET studies is also that objective measures of health don’t improve despite improvement on self rated parameters of health, which raises the question of whether these studies are not merely documenting the placebo effect in action.

    1. Health-related quality of life in patients with chronic fatigue syndrome: group cognitive behavioural therapy and graded exercise versus usual treatment. A randomised controlled trial with 1 year of follow-up. http://www.ncbi.nlm.nih.gov/pubmed/21234629


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