Vioxx was a best-selling drug before Merck pulled it from the market in 2004 over evidence linking it to heart attacks. Last fall the company agreed to a $4.85 billion settlement to resolve tens of thousands of lawsuits filed by former Vioxx patients or their families.

The lead author of Wednesday’s article, Dr. Joseph S. Ross of the Mount Sinai School of Medicine in New York, said a close look at the Merck documents raised broad questions about the validity of much of the drug industry’s published research, because the ghostwriting practice appears to be widespread.

“It almost calls into question all legitimate research that’s been conducted by the pharmaceutical industry with the academic physician,” Dr. Ross said, whose article, written with colleagues, was published Wednesday in JAMA, the journal of the American Medical Assocation.