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OTTAWA - Pharmaceutical companies are deceiving patients and doctors by keeping negative results from drug trials "locked in the filing cabinet," Can-ada's leading medical journal warns.

The Canadian Medical Association Journal says Health Canada is complicit in this "file drawer phenomenon" by too often keeping quiet about buried evidence that questions drug safety and effectiveness.

In an editorial published today, the CMAJ accuses drug companies of silencing medical researchers by having them sign agreements that suppress the release of negative findings in drug trials -- sometimes for as long as a decade after the test results are in -- while positive findings are promoted.

Most "negative studies" go unreported because they showed no beneficial effects of the drug being tested. But some hold information that would hurt the drug companies.

It takes $1 billion on average to bring a new drug to market, a huge investment that "puts pressure on companies to suppress results that might slow or extinguish sales," the CMAJ says.

But by burying data, drug companies "deceive physicians, their patients and, perhaps, shareholders. Worse, such concealment is a flagrant abuse of the trust" patients put in doctors when they agree to be test subjects in medical experiments.

A leading B.C. child psychiatrist has vowed never to do another drug-company sponsored trial unless "drastic" changes are made. Three years ago, Dr. Jane Garland was shown unpublished data that suggested the antidepressant Paxil was ineffective in children -- but only after she had signed an agreement prohibiting her from sharing the information with other doctors and investigators for 10 years.

Garland, head of the Mood and Anxiety Disorders Clinic at British Columbia's Children's and Women's Hospital, was about to do a study testing Paxil on children with mood disorders when she was sent a confidential "investigator's brochure" that summarized what GlaxoSmithKline knew about its drug.

Buried in the material were results from two studies that showed Paxil was no more effective than a placebo, or sugar pill, in treating depression in children.

At that time, the only study of Paxil in depressed children that had been published suggested a benefit. None of the Paxil-like drugs have been approved in Canada for use in anyone under 18, but they're increasingly being prescribed to children as young as three for depression, obsessive-compulsive disorder, social phobia and anxiety.

"My jaw dropped because I already signed a form saying I can't reveal anything I'm about to see," says Garland, whose commentary is one of several articles on the burying of clinical evidence in today's CMAJ.

"I do the continuing medical education (for doctors). I run the specialty clinic for the province. I teach students and residents and I have to tell them that the medication works based on the one study published, and I'm not allowed to mention that I've seen the other data. It felt terrible."

The evidence came to light last summer, when GlaxoSmithKline warned doctors Paxil should not be given to children because several large trials also found that two to three per cent of children taking the drug developed suicidal thoughts while on the medication, twice as many as children on a placebo.

Last month, Health Canada issued a public advisory about the increased risk of suicide in children for all

SSRIs (Selective Serotonin Reuptake Inhibitors).

Garland says the safety data involving Paxil had been available at least since the 1990s. She estimates 10,000 to 15,000 B.C. children are taking the drugs.

In a written response to a request for an interview, the company said it "began communicating results" from its pediatric studies in 1998 through posters, abstracts and other publications.

"GSK takes very seriously our responsibility to provide health-care professionals the information they need to prescribe medicines. We are devoting significant time and energy to finalize the process of communicating study results so that we have a sound and sustainable policy."

But the problem of hidden drug information is much more widespread, says CMAJ editor Dr. John Hoey.

"It means that physicians who are prescribing these drugs may not have complete information about how good the drug is, does it work or, equally important, how safe is it," Hoey said in an interview.

Drug companies have to make the results of all clinical trials available to Health Canada to get initial approval for a drug, Hoey says. But there is no requirement for the results to be published, or even made available to other researchers.

A Health Canada spokeswoman said that information is owned by the drug company.

Companies are required by law to report serious side effects to the government. But the secrecy in the drug-approvals process and weak systems for monitoring adverse drug reactions are also keeping unsafe medicines on the market, U.K. and Canadian researchers report in the CMAJ.

Patient reports of drug reactions are often dismissed as "anecdotal or unscientific," the researchers say. In addition, Health Canada keeps confidential any rejected applications to expand the use of a drug to another patient group, such as giving drugs designed for adults to children.

Hoey says Health Canada should pressure all drug companies to follow the lead of Merck-Frosst, which plans to publish the results of all clinical trials, regardless of the outcome.