In the mid-2000s, for example, Boris Cheskis, then a senior scientist at Wyeth Research, and his colleagues published two papers on estrogen. Later, the scientists retracted both papers, explaining that some of the data in them were “unreliable.” In 2010, the Office of Research Integrity at the federal Department of Health and Human Services ruled that Dr. Cheskis had engaged in misconduct, having falsified the figures.

Dr. Cheskis settled with the government. Although he neither accepted nor denied the charges, he agreed not to serve on any advisory boards for the United States Public Health Service and agreed to be supervised on any Public Health Service-financed research for two years.

Neither of the notices for the two retracted papers has been updated to reflect the finding of fraud. Dr. Cheskis could not be reached for comment.

Dr. Fang and his colleagues dug through other reports from the Office of Research Integrity, as well as newspaper articles and the blog Retraction Watch. All told, they reclassified 158 papers as fraudulent based on their extra research.

“We haven’t seen this level of analysis before,” said Dr. Ivan Oransky, an author of Retraction Watch and the executive editor at Reuters Health. “It confirms what we suspected.”

Dr. Oransky said he expected the rise to continue in the near future. He and his co-author, Adam Marcus, have been scrambling to keep up with new cases of fraud.

In July, for example, the Japanese Society of Anesthesiologists reported that Dr. Yoshitaka Fujii had falsified data in 172 papers. Most of those papers have yet to be officially retracted. “They’re headed for the fraud pile,” Dr. Oransky said.