By the time a new drug makes it to market, we tend to assume it's been thoroughly tested and reviewed, and is safe. There are regulations in place to ensure this, but they leave lots of room for error. And if you want to verify research for yourself, it can be really tricky or even impossible, according to a new review published in the British Medical Journal.

A group of researchers in the UK did a systematic review of the transparency policies of 42 pharma companies, including the 25 top earners. The rest of the group was a random assortment of smaller companies. They found that the vast majority (96 percent) had made public commitments to share summary results, clinical study reports, and individual patient data.

But when the researchers dug into these policies, they found companies were inconsistent and often opaque when it came to exactly how they could be held accountable.

"For example, Merck Serono stated, as a commitment: 'All Merck Serono clinical trials in patients will be considered [our emphasis] for publication in the scientific literature, regardless of outcome,'" the paper reported.

Most policies also didn't specify a timeline for how quickly the company would publish trial results, and didn't include research conducted on unlicensed medicines and off-label uses. This is troublesome because using medicines for off-label purposes is common by doctors; companies often try to market drugs for off-label uses (though, if they get caught, they have to pay hefty fines). This inconsistency in language and breadth of policies may be part of the reason why there is a lack of publicly available research data from many pharmaceutical companies.

The proportion of companies that met each of the transparency criteria. Image: Goldacre et al/BMJ

"The results of clinical trials are being routinely and legally withheld from doctors, researchers, and patients," the researchers wrote on an accompanying website, where you can explore their data yourself. "This is a longstanding problem in medicine, which we have known about since at least the 1980s; and yet it is still ongoing."

Consumers need to be able to access this information to help make informed decisions about treatment options. And to be able to judge the findings of a trial, and not just take Big Pharma and the Food and Drug Administration's word for it. But with shady, unclear policies on when, where, and how this data will be released, it's no wonder pharma companies have been able to avoid full transparency for so long.

"We hope that by auditing companies, we will help them to learn from each other, and that the companies with the poorest commitments will look to those who are doing better," the researchers wrote.