Chapter 3: The Chief Public Health Officer's report on the state of public health in Canada 2008 – Patterns of ill health and disability

Our Population, Our Health and the Distribution of Our Health

Patterns of ill health and disability

The diseases which cause the majority of premature deaths in Canada also cause ill health and disability across the population. In 2003, close to 3% of Canadians were living with some form of cancer and in 2005 roughly 5% reported having heart disease.174, 175

The proportion of Canadians living with specific diseases and health conditions varies throughout the population. The burden of disease, injury or disability also varies; some diseases are cause for concern not because they affect large proportions of the population, but because the burden on individual health and quality of life is substantial.

Although chronic diseases are most often experienced by, and associated with, older members of the population, 42% of all Canadians over the age of 11 report living with at least one of a number of diverse chronic diseases (see Figure 3.13).176, 177

In many cases, certain segments of the population are affected at different rates. For example, persons born in Canada are more likely to have any one of a number of diagnosed chronic diseases or conditions compared to those who have immigrated to Canada. This is true even after accounting for differences in age, education, and income between the two populations. Canadian-born women are three times more likely to experience a chronic disease or condition than women who have immigrated to Canada within the last four years. It is only those immigrants, men and women alike, who have lived in Canada for thirty years or more who have the same odds of experiencing a chronic disease or condition as their Canadian-born counterparts.178

Figure 3.13 Proportion of Canadians reporting one or more chronic diseases* by age group, Canada, 2005

 

Figure 3.13 Proportion of Canadians reporting one or more chronic diseases* by age group, Canada, 2005

*Diseases include asthma, arthritis or rheumatism, high blood pressure,
bronchitis, emphysema, chronic obstructive pulmonary disease (COPD),
diabetes, epilepsy, heart disease, cancer, effects of a stroke, Crohn’s disease,
colitis, Alzheimers, cataracts, glaucoma, thyroid condition, schizophrenia,
mood disorders, anxiety disorder, and eating disorder for persons aged 12+ years.

Source: Public Health Agency of Canada using Statistics Canada,
Canadian Community Health Survey, 2005.


 

Aboriginal Peoples, on the other hand, have higher rates of many chronic diseases than the Canadian average.8, 179 Figure 3.14 shows that, with few exceptions, the proportion of First Nations adults living on a reserve who report being diagnosed with some chronic conditions is higher than that of the overall population.180

Figure 3.14 Age-adjusted prevalence of chronic conditions among First Nations adults compared to the general Canadian adult population

 

Figure 3.14 Age-adjusted prevalence of chronic conditions among First Nations adults compared to the general Canadian adult population

Source: First Nations Regional Longitudinal Health Survey (RHS).


 

And as with life expectancy, infant mortality rates and PYLL, the proportion of the population living with many specific causes of ill-health and disability also differs according to factors such as income and education. For example, Figure 3.15 shows a social gradient in the prevalence of heart disease for Canadians aged 45 to 64 years by level of education.181

Other diseases and health conditions which are not necessarily the most common causes of premature death are, however, prevalent in the population and contribute significantly to the ill health of Canadians.

Figure 3.15 Self-reported heart disease by educational attainment and sex, household population aged 45-64 years, Canada, 2005

 

Figure 3.15 Self-reported heart disease by educational attainment and sex, household population aged 45-64 years, Canada, 2005

Source: Public Health Agency of Canada using Health Canada’s Data
Analysis and Information System (DAIS), Statistics Canada, Canadian
Community Health Survey (CCHS) 2005.


 

Diabetes

Approximately one in twenty Canadians has diabetes.182 The vast majority of Canadians with diabetes (about 90%) have Type 2 diabetes, which is strongly related to overweight and obesity, as well as genetics. This type of diabetes can often be prevented through exercise, healthy eating and maintaining a healthy body weight.183 A smaller proportion of diabetics with the Type 1 form, which usually begins in early life, owe their condition to a much stronger genetic component.184

As with other diseases and health conditions, certain populations experience higher than average rates of diabetes. Among First Nations adults living on reserve or in First Nations communities, the diabetes prevalence is approximately 20% − four times the rate of the general population.180

Hypertension

Hypertension, or high blood pressure as it is better known, is a major contributor to some of the top causes of death in Canada, such as heart disease and stroke.185 About 18% of Canadians aged 20 years or older report being diagnosed with high blood pressure. For those over the age of 44, the proportion climbs to 31%.186, 187 The risk of developing high blood pressure increases with age and varies by ethnicity and gender. Increasing levels of exercise, quitting smoking and improving eating habits can all reduce the risk of developing hypertension. For example, the number of Canadians with high blood pressure would be reduced by a third if everyone consumed a diet with healthy levels of sodium (i.e. levels that are significantly lower than the current average dietary intake).188, 189

Arthritis/Rheumatism

Approximately 16% of Canadians aged 12 years and older report having arthritis or rheumatism and it is the most prevalent chronic condition among First Nations adults (see Figure 3.14).177, 180 Figure 3.16 shows a social gradient for this condition, where the proportion of those reporting arthritis or rheumatism generally decreases with an increase in household level of education for those aged 45 to 64 years.187 Arthritis is not a single disease, but rather a collective term for more than 100 related rheumatic diseases – each with its own risk factors. Risk factors for the major types of arthritis and rheumatism include age, genetics, obesity, injury and autoimmune
disorders.190, 191, 192 Although arthritis is most often associated with the joints, rheumatic diseases can also affect the internal organs and skin. People living with this illness often endure years living with pain, and attempts to manage it can also lead to depression and anxiety.191, 192 In some cases, it becomes necessary for the individual to undergo joint replacement therapy. The Canadian Joint Replacement Registry reported that degenerative osteoarthritis, the most common form of arthritis from middle age onward, was responsible for 81% of primary hip replacements and 93% of primary knee replacements in 2004-2005.193

Figure 3.16 Self-reported arthritis/rheumatism by educational attainment and sex, household population aged 45-64 years, Canada, 2005

 

Figure 3.16 Self-reported arthritis/rheumatism by educational attainment and sex, household population aged 45-64 years, Canada, 2005

Source: Public Health Agency of Canada using Health Canada’s Data
Analysis and Information System (DAIS), Statistics Canada, Canadian
Community Health Survey (CCHS) 2005.


 

Obesity

Obesity currently presents a considerable health challenge in Canada (see the Chapter 2 text box “Obesity: A Public Health Approach”). It can lead to serious ill health due to its link with heart disease, cancer, Type 2 diabetes, osteoarthritis and other health outcomes.14, 195 In 2005, 24% of Canadians 18 years and older were considered to be ‘obese’ (i.e. with a body mass index equal to or above 30.0) and an additional 35% were considered ‘overweight’ (i.e. with a body mass index of 25.0 to 29.9) based on their measured height and weight.196 This is a substantial increase from the 14% reported as obese in 1978-1979.12 Obesity is not only a problem for adult Canadians; measured heights and weights of Canadian children in 2004 showed 8% of those aged 2 to 17 years as being obese and 18% as overweight.13

 

Body Mass Index, Obesity and Health Risks

The body mass index (BMI) is a ratio of weight-to-height calculated as:
BMI = weight (kg)/height (m)2.

Research studies in large groups of people have shown that the BMI can be classified into ranges associated with health risk. There are six categories of BMI ranges in the weight classification system. These are:

Classification
BMI Category
(kg/m2)
Risk of developing health problems

Underweight

<18.5

Increased

Normal weight

18.5-24.9

Least

Overweight

25.0-29.9

Increased

Obese class I

30.0-34.9

High

Obese class II

35.0-39.9

Very high

Obese class III

>=40.0

Extremely high

 

The risk of developing weight-related health problems increases the further one’s BMI falls outside the ‘normal weight’ category.194, 195

 

Given current levels of physical inactivity and poor nutritional practices (see Chapter 4), obesity rates in Canada are expected to continue to climb. Recent research has reported that obesity rates for Canadian men are among the highest in the world.197 As these rates increase, so will the frequency of ill health outcomes associated with being overweight and obese, resulting in more disability and disease and many premature deaths. It has been estimated that more than 8,000 deaths in 2004 could be attributed to obesity among Canadians aged 25 years and older.14

Differences in income and education, as well as whether an individual was born in Canada, have been linked to differences in obesity rates.178, 198 For Canadians aged 19 to 45 years, those who did not complete high school are much more likely to be obese compared to those who did complete high school or had any level of post-secondary education (see Figure 3.17).198

In terms of income levels, men and women seem to be affected differently. As shown in Figure 3.18, among those aged 46 to 65 years, obesity rates for women tend to increase as income decreases for the three groups with the highest incomes whereas, for men, obesity rates tend to increase as income increases.198 While it is not entirely clear why this relationship is reversed for men, some experts suggest that higher smoking rates and physically demanding jobs may contribute to lower rates of obesity in men with lower levels of income.

Figure 3.17 Measured obesity by educational attainment and sex, household population aged 19-45 years, Canada (excluding territories), 2004

 

Figure 3.17 Measured obesity by educational attainment and sex, household population aged 19-45 years, Canada (excluding territories), 2004

Source: Public Health Agency of Canada using Health Canada’s Data
Analysis and Information System (DAIS), Statistics Canada, Canadian
Community Health Survey (CCHS) 2004.


 

Among Aboriginal Peoples living off reserve 38% of adults and 20% of children are obese (based on measured height and weight).12, 13 For First Nations living on reserve or in First Nations communities, 36% of both adults and children are considered to be obese based on self-reported height and weight measurements.161

Self-reported data from 2005 suggest that recent immigrants to Canada have a much lower prevalence of obesity (less than 7% of that population). Immigrants who have lived in Canada for some time are more likely to be obese (roughly 13%), although their actual prevalence of obesity is still lower than the overall national rate.200 Also of note, more rural Canadians are obese than those living in urban areas (29% and 20% respectively).201

Figure 3.18 Measured obesity by income and sex, household population aged 46-65 years, Canada (excluding territories), 2004

 

Figure 3.18 Measured obesity by income and sex, household population aged 46-65 years, Canada (excluding territories), 2004

Source: Public Health Agency of Canada using Health Canada’s Data
Analysis and Information System (DAIS), Statistics Canada, Canadian
Community Health Survey (CCHS) 2004.


 

Mental illness

In 2002, almost 5% of Canadians reported having experienced symptoms consistent with a major depressive episode over the previous 12 months and 20% reported having experienced symptoms of depression, bipolar and/or a major anxiety disorder at some point in their lifetime.117, 177 The WHO estimated unipolar depression (depression without manic episodes) to be the number one single disease cause of overall ‘burden of disease’ (i.e. the impact of premature death and disability combined) in Canada in 2002.202 With the exception of bipolar disorders (i.e. depression with manic episodes), more women than men report symptoms consistent with depression and anxiety disorder in Canada (see Figure 3.19).177

Figure 3.19 Population aged 12+ years reporting select mental illnesses within a 12-month period, Canada, 2002

 

Figure 3.19 Population aged 12+ years reporting select mental illnesses within a 12-month period, Canada, 2002

Source: Public Health Agency of Canada, Centre for Chronic Disease
Prevention and Control, Health Status Indicators - Chronic Disease
Prevalences.


 

An additional concern related to mental illness is suicide, which accounted for the fourth largest number of potential years of life lost to premature mortality in 2001.116 In 2004, the suicide rate in Canada was roughly 11 suicide deaths per 100,000 population with the rate for men (17 per 100,000) more than triple the rate for women (5 per 100,000). Men aged 85 to 89 years old experience the highest rates of suicide compared to other age groups, while suicide rates for women peak between the ages of 50 to 54 years.117, 203

Infectious diseases

Rates of officially reported STIs have been on the rise in Canada in recent years, particularly chlamydia, infectious syphilis and gonorrhea. Between 1997 and 2006, reported chlamydia rates increased 78% (114 to 202/100,000), gonorrhea rates increased 122% (15 to 33/100,000) and infectious syphilis rates increased 1,050% (<1 to 5/100,000).204, 205 There is likely a combination of factors which may explain this rise. In the case of gonorrhea and chlamydia, screening rates have increased – especially among men – because of new less invasive testing. Other factors, such as increases in risky sexual behaviour, lack of knowledge regarding STI transmission and a more relaxed attitude toward safe sex practices, are also likely contributors and require further investigation. Although genital herpes and human papillomavirus (HPV) are not nationally reportable, they are also common in Canada.204 While many STIs often produce no symptoms initially, they can cause serious health consequences if left untreated, including pelvic inflammatory disease, ectopic pregnancy and infertility.206, 207 It is now known that certain types of HPV infections are responsible for almost all cases of cervical cancer.208

Some infectious diseases are more prevalent among Aboriginal Peoples than the general population. In 2006, there were 27.4 reported new active and relapsed tuberculosis cases per 100,000 in the Aboriginal population, compared to just 5 per 100,000 in the total Canadian population.209 Aboriginal Peoples also accounted for more than 27% of all reported positive HIV tests in 2006 in the 11 provinces/territories that report ethnicity with their tests, although they are estimated to make up only 6% of the population in those provinces/territories.210

Summary

Although the health of Canada’s population is considered very good – especially in comparison to many other countries – a closer inspection of differing rates of death, disease and disability among various groups show that some Canadians are experiencing worse health and a lower quality of life than others. Several forces in society influence these rates, including: the aging of the population; better medical interventions that improve survival rates for potentially fatal conditions; and a change in people’s personal choices about eating, physical activity and the use of substances such as tobacco and alcohol. These are not the only factors at play as there is good evidence that issues such as poverty, early childhood development, education, employment and working conditions, and aspects of the design and structure of communities have a profound effect on people’s individual health behaviours and health outcomes. Chapter 4 explores some of the factors that influence health and its distribution in this country.

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