Questions of bias in Medtronic-funded analysis of sterility in spine study

John Fauber of the Milwaukee Journal Sentinel, in collaboration with MedPage Today, reports another in his series of reports on conflicts of interest in health care research. It begins:

“Since 2002, the medical device company Medtronic and a group of doctors with financial ties to the company were aware that its new biological agent used in back surgery was linked to a serious complication: sterility in men.

But that information was not revealed in published manuscripts written by those doctors, a group that included orthopedic surgeons who would receive millions of dollars in various royalties from the company.
…
Now…independent researchers at Stanford University conducted a retrospective review of outcomes of patients treated at Stanford and published the findings today in The Spine Journal. The Stanford team found that in their patients use of recombinant human bone morphogenetic protein-2, or BMP-2 — marketed as Infuse by Medtronic — was associated with a measurable rate of retrograde ejaculation, a condition that causes sterility.”

And it concludes with comments from James Kang, MD, an orthopedic surgeon at the University of Pittsburgh School of Medicine, who wrote a commentary in The Spine Journal.

“Kang also questioned how two groups of researchers — the Medtronic-funded surgeons and the Stanford surgeons – could find similar rates of retrograde ejaculation in their (Infuse biologic agent) patients yet come to completely different conclusions.

He said the only rational explanation is that the Stanford researchers had no commercial conflicts of interest and the Infuse studies were corporate sponsored.

In an era of public scrutiny of surgeons’ conflicts of interest, “We must come to the hard realization that data analysis and interpretation in such studies can be biased in favor of funding sources,” Kang wrote. “After all, it is against our nature to publish a negative result or an adverse event that condemns a product that is being studied if we are being funded by the sponsors of the product.”

You can also see the story on the Milwaukee Journal-Sentinel website, complete with a document gallery in the left column.

It’s a 2,400 word story not counting the sidebars, added atop an already impressive body of work by Fauber on conflicts of interest.