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Progress Against Major Depression in Canada
Results
The proportion of persons with major depression who reported taking antidepressant
medications in the preceding month increased between 1994–1995 and 1998–1999
(Figure 1), as did the proportion who reported consulting a health professional
about their mental health (Figure 2). Between 1994–1995 and 1995–1996,
the proportion of individuals with depression receiving antidepressant
treatment increased from 18.2% (12.3% to 22.1%) in 1994–1995 to 32.6% (23.0%
to 42.2%) in 1998–1999. The increase in use is most prominent among those
with current major depression, but a positive slope also exists among persons
without major depression over time. The latter may indicate an increase
in long-term use (following resolution of a depressive episode). In keeping
with this possibility, the proportion of persons in 1994–1995 taking antidepressants
who reported taking them in 1996–1997 was slightly lower (49.7%; 95%CI,
42.7% to 56.7%) than was the proportion of persons taking antidepressants
in 1996–1997 who also reported taking them in 1998–1999 (52.4%; 95%CI,
46.6% to 58.3%). Some proportion of these subjects may also have been taking
antidepressants for reasons other than major depression.
Figure 1 Proportion of subjects taking antidepressant medications
1994–1995 to 1998–1999.
Figure 2 Proportion of subjects consulting a health professional about mental health 1994–1995 to 1998–1999.
Figure 2 suggests a decline in the number of persons without current major
depression consulting mental health professionals about mental health,
so the increasing rate observed for the subjects with major depression
cannot be discounted as a nonspecific change. When treatment utilization
is defined as either consulting a mental health professional or taking
antidepressant medications, the increase in utilization continues to be
evident (Figure 3). The proportion reporting one or more of these forms
of utilization increased from 45.7% (95%CI, 38.5% to 52.9%) in 1994–1995
to 54.9% (95% CI, 46.3% to 63.4%) in 1998–1999.
During the interval between 1994–1995 and 1996–1997, the point prevalence
of major depression appeared to decline (Figure 4). No decrease was evident
for the 1996–1997 to 1998–1999 interval. In 1994–1995, the point prevalence
was 2.4% (95%CI, 2.0% to 2.7%), which decreased to 1.8% (95%CI, 1.5% to
2.2%) in 1996–1997 and remained essentially unchanged in 1998–1999, at
1.9% (95%CI, 1.6% to 2.3%). These CIs overlap in a common range (about
2%); therefore, the NPHS data cannot be regarded as providing confirmation
that the point prevalence of major depression in Canada is declining over
time.
Discussion
In the absence of established strategies for primary prevention, most public
health initiatives that are concerned with major depression have focused
on the potential benefits of antidepressant treatment. Such initiatives
may strive to reduce stigma, to increase detection, and to optimize management
in primary care, essentially facilitating the delivery of effective treatments
to those who can benefit the most. National initiatives in the US (13)
and in Australia (19) have incorporated such goals. No such efforts are
under way in Canada. Nevertheless, the existence of a universal, publicly
funded health care system in this country should, in theory, be conducive
to the delivery of treatment to those in need. Various novel approaches
to improve the delivery of mental health services have been explored in
recent years, such as shared care initiatives, and these may have a cumulative
impact at the population level. Likewise, in this country, a series of
standardized national surveys, starting in the mid 1990s, has allowed monitoring
of key variables that relate to these aspects of public health.
Figure 3 Proportion of subjects taking an antidepressant or consulting a health professional about mental health 1994–1995 to 1998–1999
Figure 4 Point prevalence of major depression
The analysis presented here suggests progress against major depression
in Canada. The point prevalence has possibly decreased since 1994, and
the decrease has occurred at a time when treatment utilization has increased
substantially. There was no evidence of a nonspecific increase in treatment
utilization. The data suggest that treatment is increasingly reaching those
in need. Notably, the antidepressant utilization rates presented here depict
the proportion of those with current episodes who are taking antidepressants.
While the values remain fairly low (32.6% in 1998–1999), this proportion
can be expected to underestimate the true utilization rate (that is, the
proportion of those in need of treatment who are receiving it). This is
because subjects with a successful outcome from antidepressant treatment
(a remission) no longer contribute to the calculation. The increasing rate
of antidepressant use in persons without current major depression may partially
reflect remission due to antidepressant treatment.
Whether the apparent downward trend in prevalence relates to increased
treatment utilization is a difficult question—one that cannot be answered
directly using the NPHS data. Possibly, we may at least partially address
the nature of this connection using mathematical models for simulation
(20), but such approaches are in their infancy and will always be subject
to a degree of uncertainty, resulting from the many assumptions involved
in making such calculations.
The results presented here are preliminary in the sense that they reflect
only 3 time points over a period of 6 years. Trends are difficult to identify
with only 3 time points, and false interpretations can result from random
variations in rates in these circumstances. The upcoming release of subsequent
iterations of the NPHS will help to clarify some of these issues.
Funding and Support
This study was supported by a grant from the National Health Research and
Development Program (NHRDP): 6609-09-1999/2640029
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Manuscript received October 2001 and accepted March 2002.
1 Population Health Investigator, Alberta Heritage Foundation for Medical
Research. Associate Professor, Department of Community Health Sciences
and Department of Psychiatry, University of Calgary, Calgary, Alberta.
Address for correspondence: Dr S Patten, Department of Community Health
Sciences, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1.
e-mail: patten@ucalgary.ca
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