In 2002 a systematic review was conducted at the request of the US Preventive Services Task Force to determine whether routine screening improves the detection, treatment and outcome of depression.^2,3 This rigorous overview provided the basis for our review to update the Canadian task force's recommendation (Table 1). (A summary of the methods and results of the Canadian task force's review of the US task force's work, the subsequent literature update and the process of arriving at the practice recommendations are available at www.ctfphc.org.)

Depression is frequently encountered in patients in the primary care setting. The 1994/95 National Population Health Survey, a Canadian longitudinal study that included household residents in all provinces, gave a 1-year prevalence rate for major depressive disorder of about 6% among Canadians 18 years of age and older.⁸ Rates were higher among females than among males and declined in both sexes in the elderly population. Data from a province-wide Canadian community-based survey revealed a 6-month prevalence of depression of 5.9% among children 6–16 years of age.⁹ Certain subgroups of the Canadian population may be at increased risk for depression. The 2000/01 Canadian Community Health Survey showed that, after controlling for socioeconomic factors, Aboriginal people living off-reserve were 1.5 times more likely than non-Aboriginal people to have experienced an episode of depression in the previous year.¹⁰

The prevalence of major depression in Canadian primary care settings is unknown; however, in the United States point prevalence estimates of between 4.8% and 8.6% have been reported.^2,11

When making its recommendations (Table 1), the Canadian task force not only considered the effectiveness of screening tools in identifying patients with depression in primary care settings, but it also evaluated the treatment options and outcomes arising from the initial screening process, weighing at each point the potential benefits of intervention against the potential harms (including false-positive results leading to further, unnecessary diagnostic investigation). The systematic review for the US task force² found good evidence that screening for depression in the primary care setting improves detection rates. Furthermore, when screening is linked to appropriate follow-up and treatment, the overall result, based on a meta-analysis of findings from key studies, was a reduced risk of depression. However, when identification of depressed patients was not linked to follow-up and treatment, there was generally much less improvement in depressive symptoms. Evidence regarding screening adolescents and children is lacking. The available evidence led the US task force to recommend that adults be screened for depression “in clinical practices that have systems in place to assure accurate diagnosis, effective treatment, and follow-up” (grade B recommendation).¹² The Canadian task force, after reviewing this body of evidence in the Canadian context, and having ascertained that no new evidence was available, reached the same conclusion (Table 1).

“Integrated programs” as defined in the US and Canadian task force reviews went beyond feedback and included interventions such as education of patients or health care providers or both, access to case management or mental health care and telephone follow-up.¹² In deciding whether an integrated program of care for screening and treating depression exists in a community, clinicians need to examine the step-by-step process by which patients go from screening to receiving effective treatment. Given the heterogeneity of the models used in the studies reviewed, it is not possible to recommend a specific primary care-based screening and treatment program for depression. However, the following questions, with examples, may assist clinicians in determining whether integrated care exists in their community:

· Is there a mechanism to ensure that the screening results are reported to the clinician, who can then provide appropriate treatment for depression? What is the process by which the patient proceeds from screening positive to having the diagnosis confirmed to receiving treatment for depression? In the study by Katzelnick and colleagues,⁵ results of telephone screening were provided to physicians, who saw the patients at an evaluation visit and then for prescheduled follow-up sessions. Providers in the study by Wells and colleagues⁷ were asked to schedule a visit with patients 2 weeks after the initial screening.

· Is there a clinician trained in the use of antidepressants who will follow up with patients who screen positive? Is there access to psychotherapists trained in approaches effective for the treatment of depression? Evidence-based training in the management and treatment of depression was implemented in the integrated programs reviewed. For example, the study by Wells and colleagues⁷ provided a 2-day training workshop to clinical leaders (local primary care experts and nurse specialists) as well as educational materials for clinicians and patients. Furthermore, the clinical leaders provided educational sessions, including lectures and ongoing feedback, to clinicians based on medical record audits. Those in the psychotherapy intervention group of this trial had access to therapists who received specific training in cognitive behavioural therapy. In the study by Rost and colleagues,⁶ both primary care physicians and nurses received brief training in the management of depression that was aimed at enhancing the proportion of patients who completed a course of psychopharmacotherapy or psychotherapy. In each of these studies, there was strong coordination in place and a systematic process that integrated screening with treatment of depression.

Authors of the US task force review suggested that, for increased rates of screening to be translated into improved outcomes, special focus on the course of therapy may be required, “perhaps in the form of a quality improvement effort or other programs systematically designed to provide appropriate care” (page 66).³