The expulsion of an outspoken founder member of the Cochrane Collaboration has divided the international network regarded as the gold standard in unbiased reviews underpinning evidence based medicine.

On 17 September the Cochrane governing board announced it had voted to expel the head of the Nordic Cochrane Centre, Professor Peter Gøtzsche, for bringing the Cochrane Collaboration into disrepute and what it said was “repeated bad behaviour over many years”.

The board did not specify the exact reasons for his expulsion, which was followed by the resignation of four other members of the 13 strong board, but it followed the recent publication of an article by Professor Gøtzsche that claimed a Cochrane review of HPV vaccine was biased and had ignored 20 trials.

Professor Gøtzsche has previously gained a reputation for being a harsh critic of pharmaceutical industry influence in healthcare and has used his position as head of the Nordic Cochrane Centre to voice controversial views against screening mammography for breast cancer and the use of antidepressants in psychiatry.

In its statement, the Cochrane Board said the expulsion was not about scientific debate, tolerance of dissent or members being unable to criticise a Cochrane Review.

“It is about a long-term pattern of behaviour that we say is totally, and utterly, at variance with the principles and governance of the Cochrane Collaboration. This is about integrity, accountability and leadership,” they wrote.

In a lengthy statement, Professor Gøtzsche responded that the ‘bad behaviour’ justification masked a “hidden agenda” of Cochrane to remove him for his strong advocacy for transparency, democracy and scientific pluralism and against commercial pressures within the Cochrane group .

“[The] growing top-down authoritarian culture and an increasingly commercial business model that have been manifested within the Cochrane leadership over the past few years threaten the scientific, moral and social objectives of the organisation,” he wrote.

“As most people know, much of my work is not very favourable to the financial interests of the pharmaceutical industry. Because of this Cochrane has faced pressure, criticism and complaints. My expulsion is one of the results of these campaigns.”

The Cochrane board resignations triggered a huge amount of commentary among those involved in EBM and academia, with some describing it as akin to a civil war within the Cochrane Collaboration and likely to diminish or even end its role as the leading organisation for EBM.

However others have said that major disagreements should be regarded as inevitable within an organisation that has expanded rapidly from a small community of academic enthusiasts to a major multinational and bureaucratic network during its 26-year existence.

Commenting in the BMJ, Professor Trish Greenhalgh,  professor of primary care health sciences at the University of Oxford, said the Cochrane Collaboration had grown in size and influence to the point where its members required “delicate navigation of tricky political spaces and sometimes accepting hard-won compromises.”

Describing Professor Gøtzsche as an “evidence-based medicine purist” she said Cochrane Collaboration faced a philosophical challenge between passion for intellectual rigour and intellectual rigidity. What some might see as unacceptable bias that must be corrected, others might see as an inevitable and unavoidable consequence of different trial designs, populations and products, she wrote.

“I am not convinced that the Cochrane Collaboration is experiencing a crisis of either morality or democracy. Its brand, now as ever, stands for rigour, independence, and a commitment to using science to achieve high-quality patient care and social justice. We should cut it some slack while it gets its house in order.

Meanwhile, in a lengthy analysis in PLOS One, Australian EBM blogger Hilda Bastian said it would be a shame if the Cochrane ‘boilover’ caused collateral damage on confidence in HPV vaccination from “someone’s ideological war or ego battle”.

“Cochrane, you have powerful methods for finding out where the evidence takes us and updating reviews and methods in response to new evidence and criticism. Don’t let attacks and wounded feelings take you off course,” she wrote.