Chapter 5

Determinants of
Cardiovascular Health

A wide variety of factors interact to influence health: income and social status, social support networks, education, employment and working conditions, social environments, physical environments, personal health practices and coping skills, healthy child development, biology and genetic endowment, health services, gender, and culture.    Some of these, such as personal health practices, relate to the individual alone.  Others, such as social environments, relate to the environment in which the individual lives.  

Chapter 5 explores the relationship between three of these determinants associated with cardiovascular disease: education, income and personal health practices.  The latter include the risk factors included in Chapter 1: smoking, physical inactivity, inadequate consumption of fruits and vegetables, being overweight, and the two health conditions associated with these risk factors (diabetes and high blood pressure).

Income and education influence the adoption of healthy behaviours.  Increased income permits a wider array of lifestyle choices that can influence health.  Higher levels of education not only increase knowledge and skills specific to healthy behaviours, but also provide access to more lucrative employment. 

Individuals who live in poverty must cope with the daily stress of meeting basic needs.  Lifestyle choices, such as smoking, may be adopted to help cope with this stress.  Lack of income may limit an individual’s ability to purchase healthy food, which in turn may lead to health problems.  Likewise, the individual may lack the income to purchase medication that would improve a health problem such as high blood pressure.

This chapter also explores the relationship between cardiovascular disease mortality and neighbourhood income levels.  While there are other outcomes of interest, mortality data are readily available.

Canadian Data

Modifiable Risk Factors and Income

As demonstrated in Chapter 1, according to the 2000 Canadian Community Health Survey (CCHS), physical inactivity, being overweight, inadequate consumption of fruits and vegetables, smoking, and self-reported high blood pressure and diabetes were associated with income adequacy (Table 5-1).  With the exception of men who were overweight, a lower percentage of individuals in the highest income category than in the lowest income adequacy category reported each factor.

A significantly lower percentage of women in the highest income group than those in the upper middle income group reported each of the risk factors.  This pattern was not as strong among men, where only 3 of the 6 factors showed the same association.

Many risk factors showed similar prevalence rates with the two lower income groups.  Among women only 2 of 6 were different, and among men only 1 out of the 6 risk factors was significantly different.

For only one risk factor, physical inactivity, was the pattern among the income groups identical for men and women.  For being overweight, the pattern was diametrically opposed.  While the proportion of women who were overweight decreased with increasing income, the reverse occurred among men.

Modifiable Risk Factors and Education

The pattern of risk factors by level of education was not as consistent as by income (Table 5-2).  Some factors had the highest association with individuals who had completed secondary education.  Others had the highest association with those who had less than secondary education.  Overall, however, individuals with a post-secondary degree or diploma had lower prevalence rates of all risk factors than those with less than secondary education.

The percentages of both men and women with high blood pressure and diabetes were much higher among individuals with less than secondary education than for any with another education level.

 Table 5 - 1

Table 5-1        Modifiable Risk Factors for Cardiovascular Disease by Income Adequacy and Sex, Canada, 2000

Risk Factor

Income Adequacy Category

 

Lowest

Stat. Sig.

Lower Middle

Stat. Sig.

Upper Middle

Stat. Sig.

Highest

Women

 

 

 

 

 

 

 

Tobacco Smoking (Current)
Daily and occasional; age 20+ years

33.2

*

26.4

 

25.1

*

19.7**

Physical Inactivity
Age 12+ years

64.4

 

63.1

*

56.7

*

48.9**

Overweight
BMI > 25.0; age 20-59 years

42.3

 

42.4

 

40.3

*

35.9**

Inadequate Consumption of Fruits and Vegetables
Age 12+ years

62.5

*

59.4

*

56.6

*

52.4**

High Blood Pressure
Age 20+ years

21.2

 

20.3

*

14.5

*

9.3**

Diabetes
Age 20+ years

7.7

 

6.5

*

3.4

*

1.8**

Men

 

 

 

 

 

 

 

Tobacco Smoking (Current)
Daily and occasional; age 20+ years

42.7

*

33.0

*

30.2

*

24.0**

Physical Inactivity
Age 12+ years

53.9

 

56.3

*

51.6

*

43.1**

Overweight
BMI > 25.0; age 20-59 years

47.8

 

50.6

*

56.0

*

60.4**

Inadequate Consumption of Fruits and Vegetables
Age 12+ years

71.3

 

68.8

 

68.6

*

66.0**

High Blood Pressure
Age 20+ years

14.4

 

15.7

*

12.7

 

11.3**

Diabetes
Age 20+ years

6.4

 

7.3

*

4.5

 

3.7**

*Difference in values in adjacent income categories is statistically significant (p<0.05).

**             Statistically significant difference between the highest and lowest income quintiles (p<0.05). 

Source:  Statistics Canada, Canadian Community Health Survey

 

 

Table 5 - 2

Table 5-2        Modifiable Risk Factors for Cardiovascular Disease by Education and Sex, Canada, 2000

Risk Factor

Level of Education Completed

 

Less than Secondary

Stat. Sig.

Secondary

 

Stat. Sig.

Some Post-secondary

Stat. Sig.

Post-secondary

Women

 

 

 

 

 

 

 

Tobacco Smoking (Current)
Daily and occasional; age 20+ years

26.9

 

27.8

 

29.7

*

20.7**

Physical Inactivity
Age 12+ years

59.8

 

60.8

*

53.6

 

54.2**

Overweight
BMI > 25.0; age 20-59 years

51.4

*

41.4

*

36.8

 

35.3**

Inadequate Consumption of Fruits and Vegetables
Age 12+ years

60.6

 

61.3

 

58.4

*

52.3**

High Blood Pressure
Age 20+ years

30.0

*

14.8

*

10.7

 

10.4**

Diabetes
Age 20+ years

9.1

*

3.9

 

3.0

 

2.7**

Men

 

 

 

 

 

 

 

Tobacco Smoking (Current)
Daily and occasional; age 20+ years

37.1

 

34.8

 

32.2

*

24.1**

Physical Inactivity
Age 12+ years

48.9

*

52.6

*

46.8

 

49.4**

Overweight
BMI > 25.0; age 20-59 years

57.4

 

56.1

*

49.6

*

55.5**

Inadequate Consumption of Fruits and Vegetables
Age 12+ years

68.0

*

71.5

 

68.1

 

66.6

High Blood Pressure
Age 20+ years

19.3

*

11.6

*

9.5

*

11.3**

Diabetes
Age 20+ years

8.9

*

3.8

 

3.9

 

3.9**

*Difference in values in adjacent income categories is statistically significant (p<0.05).

**Statistically significant difference between the highest and lowest education levels (p<0.05).

Source:      Statistics Canada, Canadian Community Health Survey

 

Mortality

Potential Years of Life Lost (PYLL) are calculated by subtracting the age of an individual's death from age 75, based on the assumption of a life expectancy of at least 75 years. 

In 1996, the most important contributors to PYLL were all cancers (30.9%), injuries (19.2%) and cardiovascular diseases (17.6%).  People with low income were more likely than people with high income to die before the age of 75 years.  This means that preventing cardiovascular diseases and cardiovascular disease death among low income individuals can begin to close the gap between rich and poor mortality rates prior to age 75.

Among men, age-standardized mortality rates in 1971 due to ischemic heart disease were much higher among the lowest neighbourhood income quintile (Figure 5-1).  The mortality rates for all income groups have decreased since that time.  Although a difference between the highest and lowest income groups still existed in 1996, it had narrowed considerably.

Figure 5 - 1


Women showed a similar pattern to men in mortality due to ischemic heart disease in 1971 (Figure 5-2).  The mortality rates among all income groups decreased to 1996, but the relationship between the quintiles changed, so that the three upper quintiles had very similar mortality rates.

Figure 5 - 2


Diabetes is an important risk factor for cardiovascular diseases.  Between 1971 and 1986, mortality rates due to diabetes decreased among men in all but the 2nd highest income quintile, and then increased steadily over the next decade (Figure 5-3).  By 1996, the mortality rate among the lowest income quintile had increased to a point above that in 1971, and the difference between the highest and lowest income quintiles had become much greater.

Figure 5 - 3


From 1971 to 1996, mortality rates among women due to diabetes decreased in all income quintiles (Figure 5-4).  However, from 1986 to 1996, rates among women in the lowest income quintile increased while rates for women in other quintiles remained relatively stable.

Figure 5 - 4


Discussion

Several international studies have concluded that in order to reduce the incidence of and mortality due to heart disease, primary prevention programs must address socio-economic inequalities.

Ischemic heart disease mortality, including premature death, correlates with neighbourhood income, with the wealthiest quintile having the lowest rates and the poorest quintile the highest.  Differences in health care after acute myocardial infarction are not responsible for most of the differences in survival across socio-economic categories. Thus, socio-economic differences in mortality rates for ischemic heart disease appear to be due primarily to differences in incidence rather than in treatment and survival.

The analysis of the CCHS data provides one possible reason for the income disparity in mortality rates.  Individuals in the lowest income quintile had a higher proportion of risk factors than those in the highest quintile.  To be effective, then, preventive policies must address socio-economic disparities. 

The increasingly higher mortality rates due to diabetes in the lowest income group may indicate higher rates of diabetes among low income groups.  Since diabetes is a risk factor for ischemic heart disease, low income individuals with diabetes are also at increased risk for ischemic heart disease.

Public policies can mediate the effect of inequities in risk for cardiovascular diseases by decreasing exposure to risk factors or facilitating the adoption of healthy behaviours.  For example, regulating exposure to environmental tobacco smoke in the service industry, where wages tend to be lower compared to other occupations, would reduce the risk of cardiovascular diseases by decreasing exposure to a risk factor and encouraging smoking cessation. 

As a prerequisite to developing effective interventions, research is also required to provide a better understanding of the way in which socio-economic differences mediate their effects on outcomes.

Given the importance of the social determinants of health, the ability to report mortality and morbidity data linked to individual and family level socio-economic characteristics, such as education, occupation, race, ethnicity and period of immigration, is a desirable, essential component of a cardiovascular disease surveillance system.

Implications for Action

·               Implement policies to address the socio-economic determinants of cardiovascular health. 

·               Target interventions to individuals in low income groups, where the prevalence of risk factors is high.

·               Conduct research to identify reasons for socio-economic differences in cardiovascular risk factors and health outcomes. 

·               Include socio-economic indicators of health in the cardiovascular surveillance system.