Ever wonder how Glaxo was able to respond so quickly and authoritatively to the controversial meta-analysis published last May in The New England Journal of Medicine? This was the study linking the Avandia diabetes pill to a 43 percent increased risk in heart attacks and strokes. Well, it turns out that a peer reviewer for the journal broke confidentiality and leaked the damaging analysis to Glaxo ahead of publication, according to Nature (subscription required).

Exactly 17 days earlier, Steven Haffner of the University of Texas Health Science Center at San Antonio faxed his copy of the article to Alexander Cobitz, a Glaxo employee who Haffner knew from working on an earlier Avandia clinical trial. “Why I sent it is a mystery,” Haffner told Nature. “I don’t really understand it. I wasn’t feeling well. It was bad judgement.” He adds that Cobitz didn’t ask to see the draft and was “probably a bystander.”

A Glaxo spokeswoman, Nancy Pekarek, tells Nature the drugmaker didn’t offer any input to Haffner about the NEJM analysis, and that she wasn’t aware of anyone at Glaxo informing the journal of the confidentiality breach. Haffner, Nature writes, had earlier served on the steering committee of a Glaxo- sponsored Avandia trial. He says that he’s given many talks for Glaxo, but declined to say how much he was paid. “I’ve got a considerable amount of money,” he tells the mag. “I didn’t do it to raise my income or anything like that.”

Meanwhile, Chuck Grassley, the Republican from Iowa who sits on the Senate Finance Committee and probes drugmakers, has sent this letter to Glaxo to learn what Glaxo did with the leaked info.

Glaxo, of course, strongly contested the study’s methodology and “strongly disagreed” with its conclusions, Nature notes. Then, on June 5, Glaxo-sponsored researchers published in the journal’s online edition an interim analysis of the drugmaker’s own Record trial, a prospective study launched in 2001 to monitor adverse cardiac events. The June report referenced the May study and maintained the new data Record data “were insufficient” to determine whether Avandia increased the risk of a heart attack, Nature writes.

As Nature points out, the interim Record analysis was published just 15 days after the NEJM analysis. Pekarek says Glaxo’s advance knowledge of the NEJM study “added an additional sense of urgency” that prompted the fast publication. Karen Pederson, an NEJM spokeswoman, tells Nature that the journal doesn’t discuss specific peer reviewers, but adds that any reviewer who breaks confidentiality is banned from future reviewing and from contributing editorials and review articles.