Johnson & Johnson and Yale will cooperate in a major research effort. Bloomberg News

In a significant move toward greater transparency in drug research, Johnson & Johnson said it signed an agreement with Yale University under which the company will share detailed clinical trial data from hundreds of drugs and other products with outside academic researchers.

Under the unusual arrangement, Yale will vet proposals from scientists who want to conduct safety, efficacy and other studies of the treatments and determine, without input from J&J, which researchers will be given access to the clinical data.

"The medical scientific community and population at large want to have more transparency on what we do," said Paul Stoffels, J&J's chief scientific officer and world-wide chairman for pharmaceuticals. "To get really credible, we took the leap" to set up an "independent way to make sure people get access to the data."

In addition to trying to restore trust in the data, the effort is expected to help advance medical science, the company said. Independent researchers, for instance, might scour the data for subgroups of patients more likely to benefit from a drug, or be at heightened risk of side effects.

The move is the latest and one of the boldest efforts by the pharmaceutical industry intended in part to help build confidence in the reliability of clinical data supporting approval of its medicines. Over the past decade, drug companies have often been embroiled in controversies over whether published studies overstate the benefits of drugs and, especially, whether negative findings are hidden or played down, leaving doctors and patients with an incomplete picture on the risks and benefits of medicines.

Such episodes have prompted calls for more disclosure on the conduct of studies and publication of their results. All clinical trials are now required to be registered in advance on the government website, and most medical journal editors won't publish results from unregistered studies.

For the industry's part, this month a joint project by the two leading industry trade groups—Pharmaceutical Research and Manufacturers of America and the European Federation of Pharmaceutical Industries and Associations—began an effort called Principles for Responsible Clinical Trial Data Sharing to make more clinical trial data available to outside researchers.

GlaxoSmithKline PLC and Roche Holding AG are among companies that announced their own initiatives in the past year.

Under the new J&J agreement, data from all of the company's pharmaceutical products approved in the U.S. and Europe will be available to researchers. The company is taking steps to eventually include similar data from clinical trials of medical devices and over-the-counter products. All data will be stripped of any information that could lead to patients being identified.The company won't be involved in deciding which applicants merit access to the study information.

"They are sharing their entire trove of clinical trial data assets and they have given us complete authority and jurisdiction over all decisions regarding data access," said Harlan Krumholz, a Yale cardiologist and head of the Yale Open Data Access Project, which is overseeing the effort. "That's a remarkable action."

Dr. Krumholz, a proponent of so-called open science and often an industry critic, has long argued that patients and doctors need more information than is typically available from published industry studies to make informed decisions about prescription medicines.

In 2011, Dr. Krumholz and the YODA Project, under a grant from Medtronic Inc., commissioned two independent reviews of Medtronic's spine treatment called Infuse Bone Graft. A medical journal article had found that several studies of the treatment had been conducted by surgeons with strong economic ties to the company and had failed to report serious complications. The two reviews, published last year, found that the treatment wasn't any better than conventional back surgery. Medtronic said at the time it believed the reviews supported approved uses in a spine procedure.

The data that will be available to researchers under J&J's initiative and other efforts involve studies of drugs already on the market. The data troves include individual patient reports and are far more detailed than what is found in the summary papers published in leading medical journals.

Such data can be "very powerful" in giving researchers an opportunity to make a more accurate assessment of the benefits of a treatment and of any side effects that might have been missed, said Ben Goldacre, author of books critical of how drug research is conducted and a leader of a campaign to make public the results of all clinical trials. He isn't involved with the J&J-Yale project.

But he cautioned that truly useful data that goes back five or 10 years may not be in a form that is easy to review. A company might not have converted paper records to electronic form or it might reside on floppy disks, for instance, he said.

J&J's path to the new pact began when Joanne Waldstreicher, the company's chief medical officer, heard Dr. Krumholz speak about the need for open access to industry trial data. The two had been classmates at Harvard Medical School years before and he invited her to Yale to discuss the issue further.

During a long walk on the Yale campus, both doctors said, Dr. Krumholz told her he was disappointed that more companies weren't showing more leadership in making their data available for independent research.

Dr. Krumholz said that by not making such data "more widely available, we were compromising the promise" patients made to contribute to the good of society by participating in the studies.

Dr. Waldstreicher took the argument to the company, which led to the new agreement.

Write to Ron Winslow at and Jonathan D. Rockoff at