Tests for depression deemed unreliable
McGill researcher examines common surveys doctors administer to children
Common surveys used to screen for depression in children and teenagers are unreliable and may lead to misdiagnoses, a study in the Canadian Journal of Psychiatry says.
Because general practitioners in Canada and the U.S. are increasingly using short questionnaires to identify depression in pediatric patients, Brett Thombs, a clinical epidemiologist and psychologist in Montreal, set out to systematically review 20 screening tests to see how accurately they diagnosed depression in children ages 6 to 18.
“Our study shows that if depression screening were carried out using existing screening tools, many nondepressed children and adolescents would be mistakenly identified as depressed,” said Thombs, who is affiliated with the Jewish General Hospital’s Lady Davis Institute for Medical Research and McGill University’s Faculty of Medicine.
Thombs’ review found that one popular depression-screening questionnaire developed by a major drug company was accurate 78 per cent of the time.
In other words, 22 per cent of kids who didn’t have depression screened positive.
“There is no evidence they can come close to giving valid diagnoses,” Thombs told the Star.
“When used properly, psychiatric medications can help people. When used on kids who don’t have the diagnosis, they won’t see the benefit but they will face all the side effects.”
Thombs is also concerned about the effect screening would have on a health system that is already strained for resources.
“We have a terrible problem taking care of kids who have really serious mental health needs,” said Thombs. “They’re seeing a generalist or family doctor or not getting care at all or they’re on a terribly long waiting list. Or they’re prescribed medications when behavioural treatments would work better but they’re not able to access those treatments because of wait lists or insurance problems. If we’re going to bring in massive numbers of kids whose needs aren’t as recognizable, we have to ask, ‘Who are we going to treat less?’”
Earlier this year, a federal task force in the U.S. recommended routine depression screening for adolescents in primary care settings.
In Canada, provincial governments in Alberta, British Columbia and Manitoba have called for widespread depression screening. Thombs — who conducted the review with colleagues in Quebec, Ontario, Manitoba and Alberta — said he’s spoken with primary care physicians who are using the screening questionnaires not as a stepping stone to a deeper investigation that includes a lengthy diagnostic interview but to confirm a diagnosis of depression and prescribe medication.
“Hopefully, there aren’t many service providers out there who would administer a questionnaire and prescribe medication based on that questionnaire,” said Joanna Henderson, a clinical psychologist and scientist in the child, youth and family program at the Centre for Addiction and Mental Health in Toronto.
Henderson has worked with communities across the country to implement a screening tool that targets both addiction and mental health issues, opening the door so these conditions can be treated together.
“Hopefully, there aren’t many service providers out there who would administer a questionnaire and prescribe medication based on that questionnaire.” DR. JOANNA HENDERSON CLINICAL PSYCHOLOGIST AND SCIENTIST
The screening tool she used wasn’t evaluated in Thombs’ review.
She sees screening tools not as a path to diagnosis and drugs but as an important way to identify young people in distress and align them with services that can help. “We know that many young people experiencing difficulties don’t reach out for assistance. Often, by the time young people do receive treatment, they’re far along in their difficulties.”
“I think it’s clear from this review that more work needs to be done,” Henderson said. “We wouldn’t recommend that any service provider, physician or non-physician, use only a screening tool to base their treatment plan on. The intention of a screening tool . . . is to identify which young people need more attention. Which young people should have a further assessment of what’s going on? Based on that assessment, we make treatment recommendations, which may or may not include medication.”
The number of high school students who reported taking prescription drugs for anxiety and/or depression has doubled to 6 per cent (39,300) since 2001, according to CAMH’s latest annual survey on drug use and health among Ontario students.
Nearly 20 per cent of Ontario students rated their mental health as fair or poor, up from 11 per cent in 2007.