Letters to the Editor
The Association of Depressed Affect and Stroke in Institutionalized Canadians
Dear Editor:
Depression following stroke is common, with a reported prevalence ranging
between 25% and 46% (1). Depression may adversely affect functioning, recovery,
and survival and may increase the risk of stroke morbidity and mortality.
The Canadian National Population Health Survey (NPHS) has 2 components:
a household component and an institutional component. A previous analysis
of stroke data from the NPHS was based exclusively on the household component,
and the number of subjects reporting stroke and depression was too low
to support a statistical analysis (2). Statistics Canada has now released
the data for the institutional component, and it is now possible to evaluate
the association between stroke and depression in a national sample of institutionalized
adults.
The target population for the 1996–1997 NPHS institution survey included
all long-term residents of health institutions in Canada, excluding the
territories, Indian reserves, and Canadian Forces bases (3). Data collection
was carried out by personal interview, where possible, or by proxy interview,
when required because of illness or incapacity (59.1% of interviews were
completed by proxy). The sample consisted of 2118 individuals representing
a target population estimated at 222 967. The institutional response rate
for this survey was 100% (n = 213), and the individual response rate was
88.9%. We used a single item to evaluate depression: “How would you describe
yourself as being usually?” Subjects who responded “unhappy, with little
interest in life” and “so unhappy that life is not worthwhile” were regarded
as suffering from depression. The survey interview also included a question
asking, “Do you suffer from the effects of a stroke, such as paralysis
or speech problems diagnosed by a health professional?” Finally, an item
asked whether the subject had been diagnosed with a mental disorder by
a health professional. Statistical analysis employed procedures recommended
by Statistics Canada to account for the survey sampling procedures.
Very substantial proportions in this population reported depression and
stroke: 16.1% and 20.1%, respectively. Depression was approximately twice
as common in those with stroke (22.7%; 95%CI, 21.5% to 23.9%) as in those
without stroke (12.8%; 95%CI, 10.9% to 14.6%). The association was equally
evident in men and women and persisted after stratification for age (that
is, over or under age 70 years).
The major weakness of the NPHS institution depression data is the measurement
of mood status, which is based on a single self-report item. To address
this, we identified the subset of those subjects reporting depression who
also reported having had a mental disorder diagnosed by a health professional;
5.4% of persons with stroke fell into this category (95%CI, 3.5% to 7.3%),
compared with 2.9% of those not reporting the effects of a stroke (95%CI,
2.1% to 3.7%). The rates are much different, but the approximate doubling
of prevalence is still evident.
This analysis confirms, as expected, that stroke is strongly associated
with depression in residents of health care institutions in Canada.
References
1. Robinson RG. Prevalence of depressive disorder In: Robinson RG, editor.
The clinical neuropsychiatry of stroke. Cambridge (UK): Cambridge University
Press; 1998. p 53–9.
2. Hodgson C. Prevalence and disabilities of community-living seniors who
report the effects of stroke. CMAJ 1998;159 (6 Suppl):S9–S14.
3. Statistics Canada, Health Statistics Division. National population health
survey 1996–1997. Health institutions, public use microdata file documentation.
Ottawa: Minister of Supply and Services; 1999.
SB Patten, MD, PhD
R Ramasubbu, MD, Msc
JSA Simpson, PhD, MD
Calgary, Alberta
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