Dementia and ischemic heart disease comorbidity among Canadians aged 65 years and older

Ischemic heart disease (IHD), also known as coronary artery disease or coronary heart disease, is the most common type of heart disease. Plaque, composed of fat, cholesterol and other substances, builds on the inner wall of coronary arteries over time and leads to narrowed arteries. As a result, blood flow to the heart or other parts of the body may be blocked or reduced, which can cause a heart attack or stroke.^{Footnote 5}

Comorbidity, defined as the co-occurrence of two or more conditions, is associated with poorer health outcomes and can make their management more challenging.^{Footnote 1} People living with any chronic condition are more likely to live with more than one condition.^{Footnote 6} Conservative estimates from self-reported data suggest that approximately 37% of Canadians aged 65 years and older have at least two of ten common chronic conditions.^{Footnote 7} A recent meta-analysis conducted in high-income countries reported that 66% of individuals ages 65 years and older had two or more chronic conditions, with the number of conditions considered ranging between 5 and 263.^{Footnote 8}

The relationship between dementia and heart disease is complex. There are several factors, including lifestyle and socio-economic ones, associated with the development and progression of dementia and heart disease individually. Further, these two conditions share common risk factors such as hypertension, diabetes, obesity, physical inactivity, high blood cholesterol, smoking, and increasing age.^{Footnote 9Footnote 10} However, evidence also suggests that IHD is an independent risk factor for dementia, specifically vascular dementia. Indeed, the risk of dementia was found to be 45% higher in individuals with IHD.^{Footnote 9}

Validated case definitions for diagnosed dementia^{Footnote 11} and diagnosed IHD,^{Footnote 12} were applied to CCDSS longitudinal data (i.e., April 1, 1996 to March 31, 2018). Among individuals aged 65 years and older in 2017–2018, coexisting dementia and IHD cases (regardless of the order of occurrence) were identified as prevalent comorbid cases.

How many Canadians aged 65 years and older have dementia and IHD (prevalence)?

Looking at the two conditions separately using 2017–2018 fiscal year data from the CCDSS, 6.7% (or 452,000) of individuals aged 65 years and older (N=6,714,000) were living with dementia, and 26.4% (or 1,775,000) were living with IHD.

Overall, in the population aged 65 years and older:

• The crude prevalence of dementia was higher in women than men (7.8% vs. 5.4%);
• Conversely, the crude prevalence of IHD was lower in women than men (21.7% vs. 32.0%).

Looking at the overlap between these two conditions, about 2.8% (or 186,000) of individuals aged 65 years and older were living with comorbid dementia and IHD, while 4.0% (or 266,000) were living with dementia, without IHD, and 23.7% (or 1,589,000) were living with IHD, without dementia (Figure 1).

Although a higher number of women aged 65 years and older had comorbid dementia and IHD than men (106,000 vs. 81,000), the age-standardized^{Note de bas de page i} prevalence was lower in women than men (2.5% vs. 2.9%), given the differences in age distribution.

Table 1 footnotes

Table 1 footnote †

To protect data confidentiality and avoid residual disclosure in the original data source, crude prevalence estimates are calculated using randomly rounded counts to an adjacent multiple of 10.

Return to table 1 footnote † referrer

Footnote *

Data from Nunavut and Northwest Territories were not available.

Return to table 1 footnote * referrer

Source: Public Health Agency of Canada, using Canadian Chronic Disease Surveillance System data files contributed by provinces and territories, February 2021.

Figure 1 - Text description

Figure 1: Crude prevalence^{Table 1 footnote †} (%) of diagnosed dementia (without IHD), IHD (without dementia) and dementia and IHD comorbidity in individuals aged 65 years and older, Canada,^{Table 1 footnote *} 2017–2018

Population	Count	Crude prevalence, %
Individuals with both dementia and IHD	186,000	2.8
Individuals with dementia, without IHD	266,000	4.0
Individuals with IHD, without dementia	1,589,000	23.7

The prevalence of dementia (without IHD) increased with age and was greater in women than in men in all age groups (Figure 2a). The prevalence of IHD (without dementia) increased with age until 89 years and was smaller in women than in men in all age groups (Figure 2b).

Table 2a footnotes

Table 2a footnote †

To protect data confidentiality and avoid residual disclosure in the original data source, crude prevalence estimates are calculated using randomly rounded counts to an adjacent multiple of 10.

Return to table 2a footnote † referrer

Footnote 2a *

Data from Nunavut and Northwest Territories were not available.

Return to table 2a footnote * referrer

Note: The 95% confidence interval shows an estimated range of values that is likely to include the true prevalence 19 times out of 20.

Source: Public Health Agency of Canada, using Canadian Chronic Disease Surveillance System data files contributed by provinces and territories, February 2021.

Figure 2a - Text description

Figure 2a: Prevalence^{Table 2 footnote †} (%) of individuals aged 65 years and older with diagnosed dementia (without IHD), by age group and sex, Canada,^{Table 2a footnote *} 2017–2018

Age group (years)	Prevalence, % (95% Confidence Interval)
	Women	Men	Total
65-69	0.6 (0.6-0.6)	0.5 (0.5-0.5)	0.5 (0.5-0.6)
70-74	1.7 (1.6-1.7)	1.4 (1.3-1.4)	1.5 (1.5-1.5)
75-79	4.0 (3.9-4.0)	3.0 (2.9-3.0)	3.5 (3.5-3.5)
80-84	7.9 (7.9-8.0)	5.5 (5.4-5.6)	6.9 (6.8-6.9)
85-89	13.2 (13.1-13.4)	8.6 (8.5-8.8)	11.4 (11.3-11.5)
90+	19.2 (19.0-19.3)	11.9 (11.7-12.0)	16.9 (16.7-17.0)

Table 2b footnotes

Table 2b footnote †

To protect data confidentiality and avoid residual disclosure in the original data source, crude prevalence estimates are calculated using randomly rounded counts to an adjacent multiple of 10.

Return to table 2b footnote † referrer

Footnote 2b *

Data from Nunavut and Northwest Territories were not available.

Return to table 2b footnote * referrer

Note: The 95% confidence interval shows an estimated range of values that is likely to include the true prevalence 19 times out of 20.

Source: Public Health Agency of Canada, using Canadian Chronic Disease Surveillance System data files contributed by provinces and territories, February 2021.

Figure 2b - Text description

Prevalence^{Table 2b footnote †} (%) of individuals aged 65 years and older with diagnosed IHD (without dementia), by age group and sex, Canada,^{Table 2b footnote *} 2017–2018

Age group (years)	Prevalence, % (95% Confidence Interval)
	Women	Men	Total
65-69	11.9 (11.8-12.0)	21.7 (21.6-21.8)	16.7 (16.6-16.7)
70-74	16.6 (16.6-16.7)	28.4 (28.3-28.6)	22.3 (22.3-22.4)
75-79	21.6 (21.5-21.8)	34.1 (34.0-34.3)	27.5 (27.4-27.6)
80-84	25.2 (25.1-25.4)	37.7 (37.5-37.9)	30.8 (30.7-30.9)
85-89	26.9 (26.7-27.0)	38.6 (38.4-38.9)	31.6 (31.5-31.8)
90+	25.7 (25.5-25.9)	36.0 (35.7-36.3)	28.9 (28.7-29.1)

The prevalence of comorbid dementia and IHD markedly increased from 0.2% in individuals aged 65 to 69 years old, to 14.2% in those aged 90 years and older (Figure 3). The prevalence of comorbid dementia and IHD was smaller in women than in men until 90 years of age, where the prevalence did not differ significantly between sexes (the sex difference in the younger age group is not displayed due to rounding).

Table 3 footnotes

Table 3 footnote †

To protect data confidentiality and avoid residual disclosure in the original data source, crude prevalence estimates are calculated using randomly rounded counts to an adjacent multiple of 10.

Return to table 3 footnote † referrer

Footnote 3 *

Data from Nunavut and Northwest Territories were not available.

Return to table 3 footnote * referrer

Note: The 95% confidence interval shows an estimated range of values that is likely to include the true prevalence 19 times out of 20.

Source: Public Health Agency of Canada, using Canadian Chronic Disease Surveillance System data files contributed by provinces and territories, February 2021.

Figure 3 - Text description

Figure 3: Prevalence^{Table 3 footnote †} (%) of individuals aged 65 years and older with both diagnosed dementia and IHD, by age group and sex, Canada,^{Table 3 footnote *} 2017–2018

Age group (years)	Prevalence, % (95% Confidence Interval)
	Women	Men	Total
65-69	0.2 (0.2-0.2)	0.2 (0.2-0.3)	0.2 (0.2-0.2)
70-74	0.6 (0.6-0.6)	0.9 (0.8-0.9)	0.7 (0.7-0.7)
75-79	1.8 (1.8-1.8)	2.4 (2.3-2.4)	2.1 (2.0-2.1)
80-84	4.3 (4.3-4.4)	5.2 (5.2-5.3)	4.7 (4.7-4.8)
85-89	8.5 (8.4-8.6)	9.5 (9.4-9.6)	8.9 (8.8-9.0)
90+	14.3 (14.2-14.5)	14.1 (13.9-14.3)	14.2 (14.1-14.4)

What are the mortality rates (due to any cause of death) among Canadians aged 65 years and older with dementia and IHD?

As people age, they are more likely to die of any cause, regardless of their dementia and IHD status. Therefore, while the all-cause mortality rates increased with age, the rate ratios (RRs) generally decreased with age.

When compared to individuals aged 65 years and older not living with either dementia or IHD (all-cause mortality rate: 18.2 per 1,000), age-standardized all-cause mortality rates and RRs were higher in individuals of the same age with at least one of the conditions:

• With IHD (without dementia): 40.8 per 1,000 and RR = 2.2;
• With dementia (without IHD): 94.8 per 1,000 and RR = 5.2; and
• With both dementia and IHD: 138.4 per 1,000 and RR = 7.6.

As observed in the general Canadian population, all-cause mortality rates by age group were generally smaller in women than men for all combinations of conditions, but the sex pattern was less consistent when looking at the RRs.

Specifically, in individuals living with dementia (without IHD) (Figure 4a), across all the age groups, there were no significant differences in RRs between sexes. In individuals living with IHD (without dementia) (Figure 4b) and those living with comorbid dementia and IHD (Figure 4c), RRs were generally higher in women than men with the sex differential decreasing across the age groups (i.e. not significantly different in some older age groups).

Table 4a footnotes

Table 4a footnote †

To protect data confidentiality and avoid residual disclosure in the original data source, crude prevalence estimates are calculated using randomly rounded counts to an adjacent multiple of 10.

Return to table 4a footnote † referrer

Footnote 4a *

Data from Nunavut and Northwest Territories were not available.

Return to table 4a footnote * referrer

Note: The 95% confidence interval shows an estimated range of values that is likely to include the true prevalence 19 times out of 20.

Source: Public Health Agency of Canada, using Canadian Chronic Disease Surveillance System data files contributed by provinces and territories, February 2021.

Figure 4a - Text description

Figure 4a: All-cause mortality rates^{Table 4a footnote †} and rate ratios in individuals aged 65 years and older with diagnosed dementia (without IHD), compared to those without either dementia or IHD, by age group and sex, Canada,^{Table 4a footnote *} 2017–2018

Age group (years)	Mortality rate per 1,000 (95% Confidence Interval)		Rate ratio: with dementia/without IHD vs. without dementia and IHD (95% Confidence Interval)
	Women	Men	Women	Men
65-69	56.2 (50.4-62.4)	74.1 (67.0-81.9)	9.3 (8.3-10.3)	8.0 (7.2-8.9)
70-74	69.6 (65.3-74.0)	88.5 (83.1-94.2)	7.7 (7.2-8.2)	6.7 (6.2-7.1)
75-79	77.8 (74.3-81.4)	108.2 (103.2-113.4)	5.7 (5.4-6.0)	5.5 (5.2-5.8)
80-84	100.2 (97.0-103.5)	142.1 (137.0-147.5)	4.9 (4.7-5.1)	4.8 (4.6-5.0)
85-89	136.8 (133.4-140.3)	186.4 (180.4-192.5)	4.0 (3.8-4.1)	3.8 (3.6-3.9)
90+	227.8 (223.7-231.9)	281.5 (273.0-290.1)	3.0 (2.9-3.1)	3.2 (3.1-3.3)

Table 4b footnotes

Table 4b footnote †

To protect data confidentiality and avoid residual disclosure in the original data source, crude prevalence estimates are calculated using randomly rounded counts to an adjacent multiple of 10.

Return to table 4b footnote † referrer

Footnote 4b *

Data from Nunavut and Northwest Territories were not available.

Return to table 4b footnote * referrer

Note: The 95% confidence interval shows an estimated range of values that is likely to include the true prevalence 19 times out of 20.

Source: Public Health Agency of Canada, using Canadian Chronic Disease Surveillance System data files contributed by provinces and territories, February 2021.

Figure 4b - Text description

Figure 4b: All-cause mortality rates^{Table 4b footnote †} and rate ratios in individuals aged 65 years and older with diagnosed IHD (without dementia), compared to those without either dementia or IHD, by age group and sex, Canada,^{Table 4b footnote *} 2017–2018

Age group (years)	Mortality rate per 1,000 (95% Confidence Interval)		Rate ratio: with IHD/without dementia vs. without dementia and IHD (95% Confidence Interval)
	Women	Men	Women	Men
65-69	18.9 (18.1-19.6)	22.0 (21.4-22.6)	3.1 (3.0-3.3)	2.3 (2.2-2.4)
70-74	24.6 (23.8-25.5)	29.2 (28.5-29.9)	2.7 (2.6-2.8)	2.2 (2.1-2.3)
75-79	33.2 (32.2-34.1)	40.3 (39.4-41.2)	2.4 (2.3-2.5)	2.1 (2.0-2.1)
80-84	45.4 (44.2-46.6)	59.7 (58.4-61.0)	2.2 (2.1-2.3)	2.0 (1.9-2.1)
85-89	70.6 (68.9-72.4)	91.1 (89.1-93.1)	2.0 (2.0-2.1)	1.8 (1.8-1.9)
90+	140.8 (138.1-143.6)	161.5 (157.9-165.3)	1.8 (1.8-1.9)	1.8 (1.8-1.9)

Table 4c footnotes

Table 4c footnote †

To protect data confidentiality and avoid residual disclosure in the original data source, crude prevalence estimates are calculated using randomly rounded counts to an adjacent multiple of 10.

Return to table 4c footnote † referrer

Footnote 4c *

Data from Nunavut and Northwest Territories were not available.

Return to table 4c footnote * referrer

Note: The 95% confidence interval shows an estimated range of values that is likely to include the true prevalence 19 times out of 20.

Source: Public Health Agency of Canada, using Canadian Chronic Disease Surveillance System data files contributed by provinces and territories, February 2021.

Figure 4c - Text description

Figure 4c: All-cause mortality rates^{Table 4c footnote †} and rate ratios in individuals aged 65 years and older with diagnosed dementia and IHD, compared to those without either dementia or IHD, by age group and sex, Canada,^{Table 4c footnote *} 2017–2018

Age group (years)	Mortality rate per 1,000 (95% Confidence Interval)		Rate ratio: with dementia and IHD vs. without dementia and IHD (95% Confidence Interval)
	Women	Men	Women	Men
65-69	100.6 (86.0-116.9)	102.0 (89.9-115.1)	16.6 (14.2-19.3)	10.8 (9.5-12.2)
70-74	106.7 (98.2-115.9)	134.2 (125.7-143.1)	11.7 (10.7-12.7)	10.1 (9.4-10.8)
75-79	115.4 (109.2-121.9)	146.0 (139.4-152.7)	8.4 (7.9-9.0)	7.4 (7.1-7.8)
80-84	142.2 (137.0-147.6)	180.9 (174.9-187.0)	7.0 (6.6-7.3)	6.1 (5.8-6.4)
85-89	186.3 (181.3-191.4)	241.1 (234.6-247.7)	5.4 (5.2-5.6)	4.9 (4.7-5.1)
90+	280.8 (275.6-286.1)	332.8 (324.3-341.4)	3.7 (3.6-3.8)	3.8 (3.6-3.9)

Conclusion

In 2017–2018, for Canadians aged 65 years and older, 2.8% (or 186,000) were living with both dementia and IHD. In addition, all-cause mortality rates were 7.6 times greater in those with dementia and IHD comorbidity compared to those without the two conditions. The prevalence of dementia and IHD comorbidity increased with age, from 0.2% in those aged 65 to 69 years to 14.2% in those aged 90 years and older.

As Canada's population of adults aged 65 years and older continues to grow rapidly, and since the risk of living with multiple chronic conditions increases with age, comorbidity is an important area of interest for public health. Comorbidity of chronic conditions, like dementia and IHD, can be associated with worse health outcomes, and requires more complex health care management. Ongoing comorbidity surveillance, such as the new data presented in this publication and that of a previous publication on dementia and stroke,^{Footnote 13} may help to better understand the co-occurrence of conditions and further support related program and services development and planning.

How to learn more about dementia and IHD

Visit:

1. Dementia
2. Surveillance of heart diseases and conditions

Get data:

CCDSS Data Tool

More:

1. Alzheimer Society of Canada
2. Heart and Stroke Foundation of Canada

Acknowledgements

This work was made possible through collaboration between PHAC and all Canadian provincial and territorial governments and expert contributions from the CCDSS Neurological Conditions Working Group and the CCDSS Heart Disease Working Group. Results and interpretations reported are those of PHAC. No endorsement by the provinces and territories is intended.