0703 GMT November 20, 2019
In fact, the researchers discovered that nearly half of all antidepressants prescribed in the province by front-line doctors were not intended to treat depression at all, but rather problems like insomnia and digestive disorders — a finding that raises questions about the use of so-called off-label prescriptions, montrealgazette.com wrote.
“A lot of the off-label use of antidepressants is not evidence-based,” said Jenna Wong, the lead author of the study and a PhD student in the Department of Epidemiology, Biostatistics and Occupational Health.
Wong noted that the antidepressant Trazodone is often prescribed for insomnia for which there is scant evidence to show it has a benefit for the sleep disorder. Other questionable off-label uses are for attention-deficit/hyperactivity disorder, night sweats and hot flashes associated with menopause and sexual dysfunction, Wong added.
The researchers analyzed more than 100,000 prescriptions for antidepressants from January 2006 to September 2015, relying on a database compiled by prominent McGill epidemiologist Robyn Tamblyn. They found that 55 percent of antidepressant prescriptions were written for depression.
The rest were for anxiety disorders (18.5 percent), insomnia (10 percent), pain (six percent) and panic disorders (four percent). Other off-label indications were for fibromyalgia, migraines, and digestive system problems — even for urinary system disorders.
“The findings indicate that the mere presence of an antidepressant prescription is a poor proxy for depression treatment, and they highlight the need to evaluate the evidence supporting off-label antidepressant use,” the authors wrote in the study published in the Journal of the American Medical Association.
Still, not all off-label use is questionable, with Wong citing the antidepressant amitriptyline for the treatment of neuropathic pain. In that particular case, however, research has been carried out demonstrating the antidepressant’s benefits for neuropathic pain; “It’s just that the drug companies have not gone through all the regulatory hoops for approval,” she added.
All the physicians who took part in the study were involved in primary care. The researchers examined prescriptions written for nearly 20,000 patients.
The study did not examine the prescriptions by psychiatrists. Wong said she doubted that as a group psychiatrists prescribe antidepressants for off-label use to the same extent.
Dr. Joel Lexchin, an emergency-room physician and drug-policy expert at York University in Toronto, said the McGill study has important lessons for primary-care physicians.
“Unless there is pretty good evidence that the off-label use is actually beneficial — and by pretty good I mean evidence that isn’t generated by the drug companies themselves — I wouldn’t use it unless it was a last resort,” Lexchin said.
He noted that previous research by Tamblyn’s group has suggested that the number of adverse events, or bad reactions, to drugs prescribed for off-label uses for which there is little scientific evidence is higher than for drugs prescribed for their intended purpose.
Asked why primary-care doctors are prescribing antidepressants for more off-label uses, Wong responded: “We have a hypothesis as to why it could be happening: the marketing and promotion by pharmaceutical companies.”
Lexchin agreed. “One of the things that may be happening — and I don’t have any proof of this — is that the companies that are making these products are promoting off-label use by having specialists talk about possible new uses of these antidepressants.
“So you have these continuing education sessions where the speakers who are associated with the companies talk about possible new uses for antidepressants for various medical conditions and are spreading the word that it’s possible to use these products in that way,” Lexchin added.
Canadians rank among the highest users of antidepressants in the world, according to a 2013 study for the Organization for Economic Cooperation and Development. That study found that consumption of antidepressants in Canada was the third-highest among 23 developed countries surveyed by the organization, with 86 doses taken daily per 1,000 people. Only Iceland (106 doses per 1,000 people) and Australia (89 doses per 1,000 people) ranked higher.