Health Canada is reviewing two new studies that show Yasmin, the country's top-selling birth control pill, may put women at a higher risk of blood clots, CBC Marketplace has learned.

The studies were published in the British Medical Journal last month and report that women taking birth control pills containing drospirenone have 2.5 to three times the risk of suffering a blood clot than women on the safest pills on the market.

Most birth control pills contain progestin and estrogen, but only a handful use the synthetic hormone drospirenone for the progestin, including Yasmin and its sister pill, Yaz, which are manufactured by German-based Bayer.

Assessing risks In an email to CBC Marketplace, a Health Canada official said the department "is evaluating the recently published studies and is looking at available information to fully assess the risk of blood clots."

The email also said Health Canada is reviewing an announcement made May 27 by the European Medicines Agency that it is updating the product information accompanying oral contraceptives containing drospirenone to inform consumers of the increased risk with Yasmin and Yaz.

For now, however, Health Canada said it "considers that the benefits outweigh the risks when drospirenone-containing contraceptives are used as directed in the Canadian Product Monograph."

Health Canada's review comes on the heels of an announcement this week by the U.S. Food and Drug Administration that it, too, is reviewing new research that raises concerns about birth control pills containing drospirenone.

The FDA safety review covers all oral contraceptives made with drospirenone and will look at the risk of blood clots to women using those products.

Growing concern about drospirenone All birth control pills carry a small risk of blood clots, but as CBC Marketplace reported earlier this year in Spinning a Pill, there are growing concerns about pills made with drospirenone.

Previous studies looking at blood clots for women taking pills containing drospirenone had conflicting findings. Two reported an increased risk of blood clots, while two — funded by Bayer — found no difference. Now, the FDA has commissioned an additional large study looking at all birth control pills and blood clot risk.

Women interviewed by CBC Marketplace said they wished they had known there was a small but significant increase in the risk of blood clots for those taking Yasmin and Yaz.

Class action lawsuits in Canada and the United States allege that drospirenone birth control pills lead to an increased risk of blood clots. Thousands of women have reported serious health issues, including pulmonary embolisms, after going on those pills. In some cases, deaths have been reported.

Bayer says its drospirenon-containing birth control pills Yasmin and Yaz carry no greater risk of blood clots.

CBC- There is growing concern among health experts about the level of influence the drug industry has on doctors' medical decisions.

Adam Hofmann, a Montreal physician and pharmaceutical industry watchdog, says most doctors are oblivious to the extent to which their decisions on patient health care are influenced by drug companies.

Hofmann, a recent graduate now working as an internal medicine specialist at Montreal’s Sacre Coeur hospital, founded the McGill University chapter of the U.S. not-for-profit group No Free Lunch while still a medical student.

The group’s aim is to try to end the practice of accepting "freebies" from drug firms in the name of continuing medical education.

Hofmann figures it’s possible to eat free nearly every day of the week in a teaching hospital like the McGill University Health Centre — and some medical residents, saddled with debt, take full advantage of that.

But he brown-bagged it on principle, from the moment he realized how hard it was to stay at arm’s-length from people with something to sell him.

Hofmann estimates as much as 70 per cent of continuing medical education activities in Canada — from hospital rounds to conferences — are sponsored by the pharmaceutical industry, which he says has a vested interest in promoting its products.

"When the only thing you have going through your head is the purple pill, the purple pill, the purple pill, when there are half a dozen other reasonable, less expensive choices that can be used for treating your patients — are you actually making the right choice?" Hofmann asks.

Few would deny that pharmaceutical firms have a role to play, to share research findings and help doctors keep abreast of the latest developments in treatments and drug therapies.

"We’re entering into new areas of personalized medicine, areas involving genetic treatments, areas involving biologics," says Declan Hamill, the vice-president of legal affairs for RX&D, the association representing Canada’s research-based pharmaceutical companies.

"Companies (that) manufacture and create these medicines know an awful lot about them."

Hamill acknowledges the financial role played by the industry in subsidizing continuing education activities leaves a potential for conflict of interest.

"That being said … it is the doctor who controls the content, not the industry," Hamill stresses.

RX&D members must adhere to a strict code of ethical practices that covers everything from dispensing samples to when doctors can be paid honorariums to speak at industry-sponsored events.

Professional orders and medical faculties have adopted codes of ethics governing continuing medical education, too. But none bar the "free lunch" that is standard fare at hospital rounds and other educational activities.

"It’s a matter of judgment," says Dr. Yves Robert, the secretary of Quebec’s Collège des Médecins, or College of Physicians.

"If you think that a sandwich can have an effect on your professional independence — it’s probably not true. Even if it’s the best sandwich, it’s still just a sandwich."

Robert says doctors are trained from the moment they enter medical school to be critical and to evaluate everything they’re told based on evidence, not influence.

But a growing number of studies show doctors may not even be conscious of their biases and where they originate.

The Association of American Medical Colleges devoted a symposium to the Scientific Basis of Influence and Reciprocity in Washington, D.C., in 2007. It drew on a wealth of research, including studies using magnetic resonance imaging to show the "level of covert subtlety" at which the brain is working when a person is offered favours.

But studies don’t have to be that sophisticated.

"There was a study in 2001 that asked med students, residents and doctors, ‘Raise your hand if you think you are influenced by pharmaceutical funding?’" recalls Hofmann.

"Sixteen per cent raised their hand. The next question was, ‘Raise your hand if you think the guy sitting next to you is influenced' — and 61 per cent raised their hand!

"None of us are immune from the thought that we are critical thinkers — or better, smarter, faster, or whatever it is," concludes Hofmann. "The guy sitting next to you actually knows the truth."